- "Humanity is feckless and I wanted to cleanse it of a millennia worth of rot it has been infected by, and I WILL DO IT!!"
- —Damien Darhk's response to the people of Star City standing up to him[src]
Damien Darhk was the leader of H.I.V.E., and a former member of the League of Assassins. He is the ex-best friend/nemesis of Ra's al Ghul, as well as a former "Heir to the Demon". When he was put on trial, he falsified his identity as Kenneth Bender, a citizen of Markovia. After H.I.V.E.'s rampage through Star City while attempting to execute Operation Genesis, Damien was finally killed by Green Arrow. However, due to Eobard Thawne's machinations and Sara Lance's carelessness, a version of Darhk from 1987 learned about his eventual defeat and his wife's death, and boarded a Time Sphere, guided by Thawne, deciding to travel through time and change his destiny.
Leaving the League
At one point, Damien and an unnamed man were horsemen of Ra's al Ghul. The former thought himself worthy of taking the mantle, though the latter was the chosen one. Damien was to be killed but managed to escape, taking with him waters of the Lazarus Pit and some loyal followers. Damien founded his own organization called H.I.V.E. to continue the league's ways the way he saw fit. He also became accustomed to the ways of sorcery, becoming well-known and feared throughout the mystic world for his power.
Ally of Nazi Germany
In 1942, Damien was approached by Eobard Thawne/Reverse-Flash, and for reasons unclear, the two became partners. Damien decided to seek out an alliance with the Nazis, helping Adolf Hitler's plot to kidnap Albert Einstein, and force him to build an atomic bomb for Nazi Germany. These plans led to the appearance of an aberration, causing a time quake. 
Aberration timeline: Damien succeeded in kidnapping Einstein and forced him to build the atomic bomb for their cause. Damien launched the bomb on New York City, while in a U-boat, through a torpedo, killing millions. World War II was still won by the Allied Forces, but on October 8th in 1947 instead, with an additional 12 million more casualties. 
Fixed timeline: Damien failed in kidnapping Einstein when the Legends found him first but the Nazis and Damien instead kidnapped Mileva Maric. After she succeeded Damien ordered the bomb put on a U-boat but they were opposed by the Legends and Damien himself was attacked by White Canary. Damien knew her training as the League of Assassins, but was confused as to why she had a vendetta against him. When the Legends were almost overrun, White Canary retreated with the team. Damien piloted the U-boat to New York but they were intercepted by the Waverider, but Damien still launched the torpedo carrying the bomb. However the Waverider intercepted the torpedo and Damien's plan was foiled. A German officer asked Darhk to try the plan again with another bomb, but Damien refused, saying that his partner wanted to move on to "other things". As the Nazis threatened Damien, the Reverse-Flash appeared and killed all of the U-boat's crew, before taking off his hood, as Damien greeted his partner. 
Association with Vandal Savage
In October 1975, Damien planned on buying a nuclear warhead from the possession of Vandal Savage, accompanied by two of his Ghosts. He put in an initial bid of $100 million, but was outbid by Martin Stein. When Damien met him he suspected Martin wasn't as he appeared as he wasn't familiar with him or his organization, as he was aware of everyone. Stein's associate Mick Rory started to get angry with him as Damien did to him, forcing Savage to intervene. As a fight ensued, he left the premises of the Norwegian military storage facility.
In early 2014 H.I.V.E. attempted to gain possession of Malcolm Merlyn's prototype earthquake generator, sending Milo Armitage to obtain it using Ben Turner/Bronze Tiger to acquire the device itself.  Then gave Gholem Qadir safe haven in Markovia to purchase it from Armitage, presumably for Qadir to take the fall in case the plan was compromised.  However the organization's plans failed when The Arrow and Roy Harper destroyed the device. 
In late 2014 Damien hired A.R.G.U.S. operative Mark Shaw to steal a secret file from A.R.G.U.S. detailing a list of all their field operatives and their families, but this plot was foiled by John Diggle.  In early 2015 Damien visited Starling City and stayed in at a hotel of which he had the entire top floor shut down and guarded by his operatives. It's unclear what his intentions were, though they were presumably related to Genesis, but Damien caught on early that Ra's was planning to destroy Starling City with the Alpha-Omega bio-weapon to kill him, and Damien left leaving behind his assistant to take the fall. 
Attacks on Star City
Later in 2015 Damien returned to Starling City, renamed "Star City" now, with a mission to see the city destroyed and sent his operatives to rob banks and jewelry stores to build up enough wealth for the operation. After accomplishing that Damien had his men steal weapons and munitions mainly from Kord Industries and began a killing spree that saw many civilians killed. Damien also managed to force the co-operation of police Captain Quentin Lance, using his daughter Laurel as leverage should he disagree, to aid him wherever he needed.
As the surviving city leaders, Quentin included, held a private meeting to discus how to combat H.I.V.E. agents, known publicly as "The Ghosts", but Damien intruded and made his intentions clear to them. He and his organization intended to let the city die and told them all to call their loved ones and say goodbye, as they would all be dead soon and left. True to his word Damien organization coordinated attacks which left D.A. Susanna poisoned and the other leaders either shot or stabbed, but deliberately had his men leave Quentin alive but with a broken arm to take suspicion off himself. Damien later assembled his men to discus the heist of cluster bombs and the recurring problem of Team Arrow and demanded Alvarez, the leader of the heist, to explain himself. However upon being unsatisfied with his excuse Damien killed him then Black Canary, Speedy and Diggle attacked but Damien was able to escape.
Damien later continued his plan to blow up the reopened train station by placing the cluster bombs on the train itself and destroyed the brakes after departure. A few miles away from their target Damien was unable to get a response from one of his men, Slater, but was confronted by an apparent impostor of The Arrow. However Damien was surprised and confused since Roy Harper/The Arrow was killed in prison months ago but regardless "The Arrow" demanded Damien stop the train. After Damien introduced himself to "The Arrow" he immediately tried to kill him but none of "The Arrow"'s shots made contact and Damien quickly subdued him, but before he could kill him Diggle intervened and knocked Damien out. However Damien vanished from the train before the two men blew it up. Damien later watched "The Arrow"'s public broadcast with him declaring his intentions to fight for the city and to be the symbol of hope the Arrow never was, and proclaimed himself the "Green Arrow". Damien later performed a blood ritual with a goblet, apparently to heal his wounds, as Quentin came to see him on his request and ordered him to make sure Green Arrow was dead before the rest of H.I.V.E. arrived.
Damien and H.I.V.E. later hired Lonnie Machin to stop Jessica Danforth from running for mayor of Star City and though Damien was impressed by his skills of masquerading, he was unimpressed by his sloppiness. However Lonnie begged for another chance to ensure Jessica did not run for mayor which Damien reluctantly agreed, but reminded him there would be no 3rd chance. However Lonnie kidnapped Jessica's daughter Madison and Damien was outraged that Lonnie had gone too far and terminated their partnership. Later Quentin barged in to tell Damien he was done with him but Damien reminded him of his daughter and provided him with Madison's location, but also reminded him the next time they meet to mind his tone.
Seeking to kill Green Arrow Mina Fayad, an operative of H.I.V.E., hired meta-human mercenary Jeremy Tell to kill him though Damien was skeptical of Jeremy's abilities, and ordered him to prove himself by killing an operative who was almost captured rather than kill himself. Tell then literally pulled a card out of the tattoo's on his arm and killed the operative and despite knowing to kill Green Arrow would be costly, Damien agreed. After Tell's first failure he scolded him and Fayad for being compromised on a mission of her own earlier and ordered Tell to kill him, as a demonstration, but Damien intercepted Tell's card and used it to kill Mina and gave Jeremy once last chance to accomplish his task.
Quentin then met with Damien in private, seeking advice on restoring Sara Lance's humanity after being revived in the Lazarus Pit. Damien gave Quentin father-to-father advice, warning him that he needed to put down Sara and send her back to the grave, the two not knowing Oliver Queen and Felicity Smoak had discovered their alliance from a surveillance photo.
Damien then tasked Quentin with using a device that would delete the names of everyone H.I.V.E had a hand in assassinating, including Andy Diggle. After the task was finished, Quentin began to question Damien about Andy, which surprised and amused the latter, who wondered why Quentin was so interested in a crime lord but nevertheless giving him a classified folder about Andy.
Team Arrow soon learned that Damien had been holding Ray Palmer captive after intercepting his distress call to Felicity in order to use his technology for their plans, even threatening to harm Felicity if he didn't cooperate. Quentin met with Damien to request magic to help Sara after her recovery with a frustrated Damien saying that he would help but that it was the last time he would ever summon him. Quentin gave the directions to Team Arrow, who had John Diggle capture Oliver in disguise as a "Ghost". They managed to successfully rescue Ray, although Oliver barely managed to escape being strangled to death by chains under control from Damien's telekinesis.
As Oliver stepped up his mayoral campaign, Damien took a more active interest when Oliver announced his plan to restore the Star City Bay area. At a Police black-tie function, Damien approached Oliver and offered his financial and PR backing in exchange for Oliver scrapping his Bay restoration project but Oliver politely rebuffed him. The following evening Damien met with Quentin to question him about his supposed disloyalty, which Damien expressly warned him against. In the meantime, Green Arrow and his team continued to plague Damien's operations in Star City culminating in a surgical strike against the HQ of the Ghosts by Green Arrow and his team in an effort to rescue Andrew Diggle. Damien quickly became aware and sardonically confronted Speedy in a hallway, throwing her off with his magical powers before attempting to siphon the life out of her. To his horror, Damien's power had no negative effect whatsoever on Speedy and instead caused Damien to release her and double over in severe pain as dark patterns spread across his face before disappearing. Damien later stood in the crowd during Oliver's presentation where he didn't decline his previous proposal much to Damien's annoyance. 
Damien later personally led a team of Ghosts to raid an A.R.G.U.S. facility to steal a chemical bomb, only to be confronted by Team Arrow, who disarm the Ghosts of their guns with a magnetic arrow. During the fighting, Damien was in the midst of draining Green Arrow's life-force when the vigilante was rescued by the Flash. He was both amused and confused about what just happened. 
Attacking Oliver Queen
Damien would later send a drone to attack the Star City bay which was in the process of being cleaned by volunteers. However, due to his actions, Oliver Queen revealed his identity to the public as well as his connection to H.I.V.E. Much to his visitors from the organization's annoyance. In an act of revenge Damien attacked Oliver's Holiday Party, and took John Diggle, Felicity Smoak, and Thea Queen. Later, as he is speaking with the visiting H.I.V.E. agents he got a call from Oliver on his phone. Oliver attempted trading himself for his friends, but Damien decided to kill them in a gas chamber to take what Oliver had to fight for. However, Black Canary and Green Arrow (Malcolm Merlyn) interfered and saved Oliver's compatriots. Damien immediately left the scene and fought with Green Arrow, only to be attacked by Oliver. After almost killing Oliver, Damien was knocked out by Malcolm and presumed dead, after the latter exploded the facility. Damien, who escaped death, showed his associates an underground cornfield, and told them the air in it was pure and breathable thanks to the algae he engineered from Star City Bay. He then told the agents it was time for them to begin Phase Four of their plan, and sent ghosts to kill Queen. While the attack was occurring, Damien returned home to his family for Christmas.
Damien confronted Green Arrow at his home, using his telekinesis to pierce Green Arrow with two arrows before learning from him that he helped rescue his wife and daughter from Lonnie Machin. Damien showed no gratitude towards this, only mentioning that he would spare him a few more weeks to enjoy time with his family. Later that night, Ruvé Adams and Damien discussed their plans for the end of the world.
After the League of Assassins was disbanded, Malcolm met with Damien. Malcolm claimed he had information on who Oliver loved more than anything, to which Damien said he had already hurt Felicity Smoak. Malcolm retorted that it was not Felicity, it is his son William that he loved the most, leaving Damien surprised.  Damien later tracked down William in Central City and kidnapped him, bringing him to Darhk's home.
In an effort to blunt Oliver Queen's campaign to clean up the city, Darhk convinced his wife Ruve to enter the mayoral race against Queen. To help her, Damien hired the "Demolition Crew" to stage an elaborate attack on a mayoral debate between Ruve and Queen with the intention of killing Queen and leaving Ruve as the only candidate. The Demolition Crew failed to come through for Damien once their activities were discovered and foiled by the Green Arrow and his team and Ruve immediately fell behind Queen in the race.
Darhk met with Felicity and Oliver with Darhk showing Oliver a video of William playing at the Darhk residence and that he had kidnapped him by proclaiming he was a friend of Samantha Clayton. Green Arrow and Vixen later attacked Darhk at his home but were both overpowered until the remaining members of Team Arrow showed up. Darhk called Oliver and using William as leverage, forced him to suspend his campaign for mayor and endorse Ruve, which he did but still found that Darhk hadn't given up William. Team Arrow learned that Darhk's source of power was a totem that Quentin had seen him praying over and attacked him at his home in order to retrieve William and destroy the totem. Vixen destroyed the totem by channeling enough strength from the animal spirits, rendering Darhk's powers useless and him easily overpowered by Green Arrow and knocked unconscious. Darhk was then promptly arrested by the SCPD.
Trial and Imprisonment
During his trial, Darhk listens on as Fitzmartin, Darhk's attorney, destroys the credibility of Diggle and Thea's testimonies by proclaiming Diggle helped her purchase $74,000 worth of cocaine with an affidavit signed by Thea's dealer. However, Fitzmartin loses the case when Quentin comes forward as a witness due to his credibility as a police chief and exposes that he had been helping Darhk commit illegal activity due to Laurel's life being threatened. Darhk is then imprisoned without bail or the possibility of release but after he is escorted into his cell, he casually pulled a ring from between his teeth and slid it into his finger before smiling, implying his plans were still in effect.
Malcolm visited Darhk in prison as the latter pondered why his resources aren't trying to help him escape prison. Malcolm informs Darhk that H.I.V.E. has turned against him due to his brutality and they are moving forward with Genesis without his help. In prison, Darhk is beaten up by Michael Amar and two of his gang members but Darhk managed to turn the tables by discovering the whereabouts of Amar's grandmother and threatening her life to turn him against his own men, who he stabs to death with a shiv in front of him, the two now working together. 
Malcolm brought Darhk his idol (the same one previously owned by Baron Reiter on Lian Yu) but the stone to power it was still separated and Darhk ordered Malcolm to hunt it down. Darhk and Murmur organize a prison riot by Murmur slipping shivs to prisoners via books and stabbing the guards in order to lure Team Arrow to the prison. There, it is revealed that Andy had been a spy for H.I.V.E. and once he learned Team Arrow was in possession of the stone, all he needed to know was its' location. With his magical powers restored, Darhk restrained Diggle, Oliver, and Laurel, also revealing that he was aware of their secret identities. Oliver shot an arrow at Darhk but he stopped it with his telekinesis and responded by stabbing Laurel in the stomach to send a message for Quentin for turning against him as Darhk, Malcolm and Andy escaped. Laurel died of the injuries Damien afflicted upon her hours later. 
Original timeline: According to Rip Hunter in the original timeline where Sara never left Star City to join his team and take on Vandal Savage in the future, Damien would have killed both her and Laurel as well as their father.
Placing a tracker on Diggle after he is kidnapped by Andy, Darhk is able to locate Lyla. Easily penetrating the secured truck with his magic, Darhk extracts the Rubicon from Lyla, a device capable of controlling any nuclear missile.
Having killed tens of thousands of people with a nuclear missile guided by the reprogrammed Rubicon, Darhk absorbed the dark energy channeled after their deaths, growing stronger than ever.
After H.I.V.E.'s rampage through Star City while attempting to execute Operation Genesis, Damien was finally killed by Green Arrow, who was able to negate Damien's dark magic by drawing on the positive faith of the people of Star City and their belief in him, both as Oliver Queen and Green Arrow.
Changing his destiny
In the new, altered timeline without Vandal Savage, Darhk tried to launch an atomic bomb on New York City in 1942 at the behest of Eobard Thawne and Adolf Hitler. The Legends were able to foil his plan by having the Waverider absorb the impact. As Damien was about to be killed by Nazi officers on U-boat, angry at his refusal to find another atomic bomb, he was saved by Eobard, who's killed the submarine's whole crew. In the year 1985, Darhk discovered what his fate is like in 2016 on Genesis Day by Sara Lance, and being saved by Eobard Thawne himself and together they could time travel to change their destinies, with the use of the Time Sphere.
Damien apparently used to be arrogant and overconfident as he believed himself to be the worthy successor to the then Ra's al Ghul. He is immensely intelligent, cunning and calculating as he managed to stay ahead of Ra's for years, evading him every time his ex-best friend tried to kill him. According to his late assistant, he is not a person who can be caught off guard so easily.
Damien is also a perfectionist carefully planning out all his schemes and expects his subordinates to follow through without any mishaps. He will ruthlessly kill them for such failures if he believes they have not performed their duties to an adequate standard. Although he demanding good manners and respect from others, he was not above mocking people and their suffering.
Damien believes that the world is resistant to change and sees himself as one who brings about progress. He views his attacks on Star City as an act of mercy comparing it to putting down a dog on the street. He believes that to build something new and great the old must first be torn down first. Despite being marked for death by his old allies in the League of Assassins he has continued to follow the philosophy of the League and carries on with his own interpretation of it through his organization, H.I.V.E..
Like many assassins, Damien is cold, cruel and ruthless but does have a sense of honor and good morals. For example, Damien has morals against torturing innocent children and says it is a line he would never cross. He became disgusted with Lonnie Machin for kidnapping Jessica Danforth's daughter Madison. Part of this might be related to Damien having a child of his own and understanding the pain of having a child in danger. Although he threatened William's life to get Oliver to give up his mayoral campaign and his attempts to fight Damien, showing he feels only he is justified in carrying out such an action whereas he was angry at Lonnie for doing the same thing, and Malcolm was the one who technically kidnap William, Damien chose not to release him from his captivity and would never have done so had Oliver not followed his instructions, and would not have harm William even if Oliver had refused to not followed his instruction; due to Damien being a parent himself. He also advised Quentin Lance to put his daughter back to her final rest as he believed that was more merciful than her enduring the consequences of her resurrection from the Lazarus Pit. He advised Quentin to do this as "one father to another".
Despite normally being serious and cruel, Damien is shown to have a definite (if sick) sense of humor. He grinned while mocking an A.R.G.U.S. guard whose life-force he was draining, declaring that it was fun and he could do it all day. Though confused when the Flash saved Green Arrow, as it happened so fast he had no idea what happened, he was also amused. His demeanor can be described as charmingly demented, as he is often quick to make light of whatever situation he is in, regardless of the danger or gravity of what is occurring. This trait typically manifests through his smiling and jovial tone of voice at times that most people would consider inappropriate or unusual. It is a rather unnerving trait that intimidates his enemies and befuddles his allies on a regular basis.
His ruthlessness was reserved for his enemies and keeping his men in place, and does not extend to his H.I.V.E. associates or family. He had protected his associates from Green Arrow, and weathered their sarcasm during setbacks without violent outbursts, such as when Oliver Queen showed his photo to the public. Where possible he will use persuasion to force his enemies to back down, only resorting to violence if they persist in getting in his way - though his methods of persuasion can themselves be quite violent.
Damien also had little tolerance for disobedience, failure and disloyalty, as multiple times he threatens to kill Quentin Lance's daughter Laurel, if he ever betrays him, eventually going through with his threat after the latter betrays him, even killed Phaedra Nixon and Milo Armitage high-ranking members of his organization for their treachery; for allowing him to rot in prison.
Despite these negative traits of his, Damien is a loving husband and father, he cares about his wife Ruvé and his daughter Nora, as he will kill anyone who dares try to harm them, he also had no tolerance for those who disrespect members of his family, as he killed Tomas for disrespecting his wife. Ultimately, once learning of his wife's death and possible demise of his daughter, Damien lost all care for a better world, seeking to destroy it all regardless of who dies.
Ruvé's death and the destruction of Genesis had wracked all of Damien's hope for humanity, gaining a nilihistic and misanthropic perspective on everything. He truly believed that humanity was diseased and lacking in strength, unity and conviction, believing that Genesis was the only opportunity for the human race to restart through a peaceful utopian society (which ironically, most of its civilians are controlled through mind control) by starting anew. Damien still believes in what he was doing, claiming his goal to "cleanse (the world) of a millennia worth of rot" but now views the world as beyond saving, and its annihilation was a mercy. His grief over Ruvè had allowed himself to be engulfed over his insanity, as he was willing to kill himself and his daughter with the rest of the world but claims in the end the two would see Ruve again.
Powers and abilities
- Dark Magic: Damien's powers came from the Khushu Idol, a totem that channels and the harnesses primordial energies of darkness (i.e. death or destruction, terror and fear). His command of this magic was such that John Constantine, a master sorcerer himself, dreaded facing Damien. The more he draws power from the idol/absorbing life, the more powerful he is in the moment. Once absorbing the combined life-force of tens of thousands of people, his power grew to levels he wasn't even aware of until seeing it in action, making him need to exercise more focus and control on using his power.
- Accelerated healing: The idol gives Damien advanced healing powers. After he was shot through the abdomen with two arrows and began bleeding out, his re-connection to his power from the idol fully restored him. The life-forces that he absorbs also seem to prevent fatigue, and near-instantly recover from the effects of toxins.
- Enhanced durability: Damien possessed inhuman resilience granted from his idol. He was shot repeatedly and was completely unharmed.
- Enhanced strength: Damien had greater strength than a regular human. He had easily outmatched the Green Arrow and threw him into a metal pole with enough force to deform it. He could also snap one of Green Arrow's arrows in half with one hand and pinned an adult human against a wall effortlessly. He was strong enough to lift fully grown humans over his head effortlessly with a single hand, as he did to Donna Smoak.
- Life-Force absorption: Damien could siphon the life-force from people and kill them, simply by touching them, aiding to the dark energy he has harnessed, increasing his powers and their duration.
- Telekinesis: Damien was able to grip, move, and generally exert great amounts of force on objects and people without physically touching them. He could stop multiple projectiles, launch them with deadly force, animate chains, and even choke groups of people. While often gestured with his hands for focus, he can effectively use this power by sight alone as he crushed a TV by doing so. To which the latter, he could even strangle someone in a different country through a video screen, suggesting he only needs to know where they are to target them. With enough dark energy, he could even disintegrate targets within a few feet of him. In Schism, his control over motion was shown to be intensified to the point where he could cause a small explosion to be frozen mid air.
- Teleportation: Damien could instantly relocate himself, letting him catch his enemies off-guard and leave the area without a trace. The range of this power, if any, is unknown.
- Longevity: Ra's al Ghul revealed that Damien stole water from the Lazarus Pit when he left the League. This has allowed Damien to live for hundreds of years without aging while maintaining his health, vitality and appearance. It is possible the waters of the Lazarus Pit have begun to lose their potency for Damien, as they did for Ra's. To which, his connection to the idol or life-force siphoning power may also have contribute to his prolonged life.
- Genius-level intellect/Master tactician/Leader: The founder and leader of H.I.V.E., Damien had been able keep his organization a secret from the world at large and avoid capture by Ra's al Ghul and the league. He had also successfully hidden his true plans from Team Arrow. Damien has displayed high intelligence and has multiple lifetimes of knowledge. He has demonstrated expertise in advanced science (despite finding it boring), and claims to have extensive knowledge of political, criminal and secret organizations.
- High tolerance for pain: Damien had a high tolerance for pain, as he was able to pull out deeply penetrated arrows from his chest, and still move and stand with little effort. This was presumably due to his League of Assassins' training.
- Master archer: In his final duel with Oliver, Damien was showed to be skill in archery. He was able to shoot an arrow directly into Oliver's chest, which would have been a killing shot if not for Oliver's armor. Damien was likely trained in archery during his time in the League.
- Master hand-to-hand combatant/Martial artist: Trained by the League, Damien was a master fighter, having been a potential successor as Ra's al Ghul. At his peak, he could fend off White Canary with only minor difficulty. However, as he began to rely solely on dark magic, his combat skill decreased considerably. When unable to use his power, he was quickly defeated by Green Arrow and likewise brought down by two prisoners in Iron Heights. Once reconnected with his powers, while Green Arrow was able to repel it with Light magic, Damien proved able to fight on par with the vigilante, initially overpowering him but ultimately was beat down by Oliver and several civilians. Back in 1942, his skill seemed to be superior to that of 2016, as he easily defeated Sara in single combat.
- League of Assassins training: Damien was a highly skilled fighter and assassin, trained in the use of a variety of melee and ranged weapons. As an "heir to the demon", his skill surpasses most, if not all other members of the League. Without his magic, he was able to fight and overpower Oliver Queen for a time.
- Occult knowledge: Because of his greatly extended life-span, Damien possessed vast knowledge of magic and mysticism. He also has knowledge and understanding of mystical objects such as the Lazarus Pits and the Anansi Totem. In fact, it is believed that the ritual he performs on the idol allows him to control it more completely without it damaging his sanity.
- Peak of human physical condition: Aside from his magically enhanced strength, Damien was in top physical condition.
- Khushu Idol: The very source of Damien's dark power was also his key weakness. If the idol is destroy, Damien will lose his powers, becoming a normal human again. If the idol can be reassembled and the sacrifice ritual is performed, it will restore Damien's powers. Damien will also lose his powers if he does not regularly absorb negative energy from others. As the idol normally corrupts all near it, to keep his sanity, Damien regularly performed a blood ritual before it. As revealed by Mari McCabe, Damien must remain in close-range to the idol to remain empowered. The idol still has a great range, as Damien still had his powers from several city blocks away.
- Light Magic: Due to the fact that Damien's magic comes from the absorption and manipulation of dark energy, if one can focus their natural life energy into positive sources of strength (i.e. hope and joy), Damien's magic will ultimately prove ineffective against the target and even physically repel him from the said person.
- Thea Queen: For reasons unknown, but presumably the Lazarus Pit, Thea was immune to Damien's life-siphoning power. When he used this power on her, he instead found his own life force depleting, severely weakening him. However, since Thea has been cured of the Lazarus Pit's effects, she is likely no longer immune to Damien's ability to drain the life force of others.
- Khushu Idol: The Khushu Idol is a mystical totem and the source of most of Damien's powers.
- Lazarus Pit water: Damien used the Lazarus Pit's waters to live well beyond his lifetime and run H.I.V.E..
DC's Legends of Tomorrow
- Damien was aware that Malcolm Merlyn was Ra's al Ghul, and that his ex-best friend is dead; implying that he had some remaining connections within the League of Assassins before the league fell, or at least kept tabs on the League as much as possible as he was a target of them for over a century. This is further shown when he is already aware of Malcolm's loss of power over the League in just one day after its disbanding.
- After his cameo in "Pilot, Part 2", Damien Darhk became the only main antagonist of Arrow (and the Second in the Arrowverse, after Vandal Savage) that appeared at least once in every main series of the Arrowverse.
- During their first confrontation, Damien immediately realized that Speedy had been trained by Malcolm; implying that he knows Malcolm (or at least his fighting style) well.
- During an argument at an arms auction in 1975, Damien was derisively nicknamed "The Master Race" by Mick Rory because of his blonde hair, blue eyes and Nazi-esque uniform. Ironically, Damien himself has stated that he personally despised the Nazis but admired their scientific pursuits.
- Damien is the second main antagonist to directly be responsible for the death of a main character following Slade Wilson. Damien interestingly referenced Slade to Oliver on how he spared him before Oliver killed Damien.
- The incantation Damien used when he uses the idol, and when he nearly died in Dark Waters is "Kanjigar Septum Vohostrum".
Behind the scenes
- In the DC comics, Damien is an enemy of the Titans responsible for reforming the H.I.V.E. into a more cohesive terrorist organization, as opposed to being a generic robe-wearing cabal. He had no magical powers like in the show, but was instead a business savvy manipulator, glued to his cell phone. He did however gain immortality after receiving blood from Deathstroke's ex-wife, Addie Wilson.
- Damien Darhk has similarities to DC's Ares: The God of War, as their powers feed on the psychic energies that come from death and conflict.
- Though, unlike Ares, Damien Darhk cannot naturally channel the dark energies caused by war and conflict. Therefore requires his Khushu Idol to do so.
- Darhk's using his telekinesis to choke people and how he can kill people with telekinesis by knowing where they are and seeing them through a video screen is similar to Darth Vader's powers, as well as his using them to intimidate and punish others.
- In the DC comics, a character named Dr. Ebeneezer Darkk was the first person other than Ra's al Ghul to lead the League of Assassins.
- Ironically, Doctor Darrk had a falling out with Ra's al Ghul, similar to the show's version of Damien Darhk, making it possible that the character is actually an amalgamation of the DC comic versions of Damien Darhk and Doctor Darrk.