- "You know, you should be careful how you treat people, my friend. After all... what goes around, comes around."
- —Digger Harkness after killing an A.R.G.U.S. security guard with a boomerang[src]
Digger Harkness was a member of ASIS, specializing in weapons and technology. During his time at the agency, Harkness trained with Slade Wilson several times. During Slade and Harkness' final fight, Slade's Mirakuru-enhanced strength returned, and he defeated Harkness.
Member of the Suicide Squad
During an operation in Tanzania, Harkness and his team were facing the warlord outgunned, so Lyla Michaels gave the call to kill them all. However, Harkness' explosive in his neck malfunctioned and didn't kill him. After this, he developed a grudge against Lyla, who had killed his team and tried to take his life.
Revenge on Lyla Michaels
Oliver Queen and Roy Harper investigated his house which was wired with explosives. An intervention team of A.R.G.U.S showed up as well. However, Harkness had left moments before. He used the identity card to get access to A.R.G.U.S where he quickly killed the security guards trying to stop him. Confronting Lyla Michaels, John Diggle and a squad of agents a huge firefight erupted where he used his boomerangs to corner Lyla and Diggle. Arsenal and The Arrow showed up and fought him. He was able to hold his own and almost hit Oliver with a boomerang when it got caught by The Flash. Realizing he was outmatched, he detonated a smoke bomb and quickly escaped the place.
Team Arrow protected Lyla and tracked down his supplier. Expecting them to come after his supplier of boomerangs, Harkness gave the cellphone used to contact him to a Russian mobster in a bar. He then traced the cellphone of his supplier back to the Arrowcave and broke in while Diggle, Barry, Roy and Oliver were gone. Confronting Lyla, he got in a firefight with her, managing to throw a boomerang into her stomach. Felicity threw an explosive at him which forced him to retreat.
Believing Lyla was dead, Harkness planted five bombs over Starling City and planned to leave by train. Suddenly, all the passengers disappeared in a blur and Arrow and The Flash were confronting him. He told them about the bombs and then activated them hoping he could escape. However, Arrow fought him while the Flash and Team Arrow dealt with the bombs. After a fierce fight, he got ultimately beat and pinned to the wall by arrows. He mocked Arrow and told him he would never tell him how to disarm the bombs. Disappointed, he realized the bombs had been disarmed already. He then mocked Arrow, stating that his refusal to kill him makes him weak. Oliver retorts that it means he still has some humanity left. As Arrow turned his back, Digger reached for a boomerang, but Arrow shot him through the hand. He was later imprisoned in the A.R.G.U.S. supermax on Lian Yu.
Temporary work with Suicide Squad
Although put in supermax, Harkness was temporarily released from Waller for having one more chance to be released if he completes a mission for them. He teamed up with Floyd Lawton and Carrie Cutter as part of the Squad. They watch The Flash's take on the meta-human Shay Lamden (The Flash: Season Zero) aka King Shark. Waller sends the team to stop him. They arrive outside of the man's former apartment and Deadshot helps to knock him down, before Cupid traps him with a net. Joe West approaches, asking who they were, before Lawton introduced them as the Suicide Squad. They each fire at him, but he is saved by Barry Allen, who rushed him to safety while the Squad appears to recognize him.
After completing this mission, Harkness expected to be released from prison, but due to his unpredictability, he was sent back to supermax on Lian Yu.
Joining Prometheus and death
Several years later in May 2017, Harkness and Slade were released by Oliver Queen to help the latter defeat Adrian Chase/Prometheus and rescue his family and friends. Harkness seemingly agreed in exchange for being set free. Oliver, Slade, and Harkness met up with Malcolm Merlyn and Nyssa al Ghul to discuss their plan of attack against Prometheus' team. Harkness made a pass at Nyssa, who threatened to "feed [him] [his] eyes" if he leered at her again, much to his amusement. Malcolm sarcastically added that Harkness wasn't even her type. Suddenly, the plane which Oliver arrived in was destroyed by an RPG. While Malcolm and Nyssa went to find the source of the RPG, Harkness, Slade, and Oliver searched for Prometheus' hostages.
When Harkness wondered why he couldn't have a weapon like Slade, Oliver replied that he trusts Slade more than the former. Harkness pointed out that Slade killed Oliver's mother, to which Oliver furiously warned Harkness not to fool with him at the risk of being put back in his prison. The trio then came upon Felicity, Thea Queen, Curtis Holt, and Samantha Clayton, who were imprisoned in cages. Suddenly, they were ambushed by Talia al Ghul and Evelyn Sharp. Harkness then pulled out a pistol, revealing he was allied with Chase all along. Harkness, Talia, and Evelyn tried to persuade Slade to join them, which the latter seemingly accepted. However, Slade then berated Harkness for simply assuming he would accept the offer and punched him. Harkness and Slade briefly fought, with Slade throwing him to the ground. When Nyssa and Malcolm arrived, Harkness and Talia escaped using a smoke bomb, leaving Evelyn behind.
Harkness and some of Talia's cult members began tracking the escaped prisoners, led by Malcolm. The group eventually caught up with Malcolm, seemingly alone. When Harkness suspiciously wondered why he was standing out in the open, Malcolm replied, "Let me show you." Malcolm then took his foot off a landmine he had been standing on, detonating it and killing Harkness, Talia's students, and himself.
Sometime before 2032, one of Digger's boomerangs was displayed within the Hall of Villains in the Flash Museum, along with other memorabilia from past villains that Team Flash had fought and defeated.
Bound on revenge, Digger was highly motivated to kill her and talked about the boomerang as a metaphor that everything comes back at you sooner or later. He was convinced that the ends justified the means and even planted bombs in the city and risked the lives of countless people to escape. He mocked Oliver for his humanity and said he did not have what it takes to stop extreme people like him.
Digger was one of the few foes to ever tactically outsmart Oliver Queen.
- Peak of human physical condition: As a former member of both ASIS and Task Force X, Digger was a very powerful and highly trained fighter. He easily defeated several A.R.G.U.S. guards and faced the Arrow, Arsenal and the Diggle family without fear, battling the first duo and knocking Roy down.
- Master combatant/Martial artist: Digger was an excellent combatant and martial artist. Using his edged boomerangs as close quarter weapons, he was able to cut down multiple armed guards in mere seconds. He was even able to fight and briefly overpower both Arsenal and the Arrow simultaneously knocking the former down and almost hitting the latter. In his final fight with the Arrow, Digger was able to easily cut all the arrows fired at him and go up against him for a time before being overpowered. His time imprisoned in Lian Yu did not seem to hamper his abilities, as in his fight with Slade Wilson, Digger was able to land several punches, though was ultimately quickly overpowered and tossed aside.
- Master boomerang wielder: Digger was a master at throwing his edged boomerangs and is able to hit moving targets with incredible precision. During firefights and combat he uses the ability of the boomerang to fly back to throw it over the cover of his opponent and then strike them in the back. Digger could also wield his boomerangs in close combat.
- High-level intellect/Master tactician: Digger was a great tactician. He was able to use his knowledge of A.R.G.U.S to break in and almost kill Lyla Michaels. He was able to lure Team Arrow away from the Arrowcave to get close to an unprotected Lyla. In an effort to leave Starling City, he planted bombs in various locations to help make sure he did. Digger was even able to tactically outsmart Oliver; a genius and master tactician in his own right.
- Explosives expert: Digger was highly skilled with explosives, having rigged five connected bombs to detonate in various locations in Star City. He specifically ensured that the bombs must be defused at the same time.
- Hacking: Digger was able to track the Arrowcave using the signal from the mobile phone that he left to Klaus Markos.
- Boomerangs: Digger used edged boomerangs to take out his targets. In close combat he uses them like cutting weapons. He also has boomerangs that are made to explode on impact from C4 in specialized grooves, acting like grenades.
- Smoke bombs: Digger used a smoke bomb to quickly escape.
- Bombs: Digger used bombs to wire his apartment and planted five of them in Starling City.
The Flash: Season Zero
Behind the scenes
- In DC comics, Captain Boomerang is an enemy of Barry Allen and Wally West, even joining the Rogues. He went on to become a member of the Suicide Squad in exchange for a pardon from all his crimes. In the Arrowverse however, Captain Boomerang is mainly an enemy of Oliver Queen since the Suicide Squad is primarily featured in .
- In the DC comics, "Digger" is simply a nickname for Captain Boomerang, his real name being George Harkness. In the Arrowverse, no other name but "Digger" has been given so far.
- Equally, in the DC comics, Digger is a somewhat buffoonish and often-ridiculed figure, whereas in the Arrowverse, he is a feared and deadly threat to the Arrow and the Flash alike.