- For his partner who uses the same signature balaclava, see Slade Wilson.
- For the issue of the same name, see "".
Bill "Billy" Wintergreen (died 2008) was a member of the Australian Secret Intelligence Service/ASIS unit, and the nemesis of Yao Fei Gulong. He was also the former friend and ex-partner of Slade Wilson, and the godfather of Joe Wilson. After he and his partner arrived on Lian Yu to rescue Fei, Billy betrayed Slade and allied himself with Edward Fyers' mercenary unit, thus tracking and hunting down the man he was originally ordered to rescue.
Agent of ASIS
Billy and Slade Wilson were best friends prior to Lian Yu. They were so close to the point Slade made Billy the godfather to his son.
In 2006, Billy and his partner and also friend, Slade, came to Lian Yu to rescue Yao Fei Gulong. Their plane was shot down, and Billy eventually allied himself with Edward Fyers, leaving Slade to escape by himself.
Working for Fyers
When Oliver was stranded on Lian Yu, he was captured by Edward Fyers' men who were looking for Yao Fei Gulong, their reasons unspecified. When Oliver refused to give up Yao's location, he was tortured by Billy. Oliver is later rescued by Yao Fei, who engages Billy in battle and temporarily subdues him, escaping with Oliver.
Billy later tracked down Yao Fei, besting him in a fight and taking him to a camp led by Edward. He was later seen fighting a prisoner in an organized fighting circle with all the other mercenaries watching. Billy throws many punches and kicks at the prisoner while the latter fails at every attempt to even touch him. Bill glances at Fyers who gives him a nod, allowing Bill to kill him.
When Oliver returned to the camp to rescue Yao Fei, Yao Fei knocked him out as Edward Fyers and Billy entered his tent. Billy was led to execute Oliver. However, Slade caused an explosion to distract everyone. Billy met Slade with vigor, eager to kill his old partner. As Oliver ran to his safety, Slade and Billy fought, leading to Slade stabbing Billy through his right eye, killing him.
Following the destruction of the Amazo, Slade was stranded back on Lian Yu and went searching for Oliver to enact his revenge on the latter. He stumbled on Fyer's former camp and discovered Wintergreen's corpse where he left it with the sword still stuck in his eye. After his return to Australia and at ASIS headquarters in Perth, Slade - not wanting to reveal the actual details about what happened on the island - lied about Wintergreen's betrayal and death to the regional head of ASIS, Wade DeForge, who was Billy's half-brother. Later on ASIS agents went to Lian Yu and discovered Billy's corpse with Slade's sword still embedded in his eye, thus exposing Slade's lies.
Billy was once a man of honor who fought for his country, but after Billy and Slade were captured by Edward Fyers, he immediately accepted Edward's offer to work for him. It was after this moment, that Billy revealed his treacherous and self-centred nature. It can also be assumed that he had a bad temper, as when Oliver called him by his name and criticized him for what he had become, as Billy brutally attacked him.
- Peak of human physical condition: Billy was in top physical condition for a man of his age; he demonstrated incredible feats of strength, durability, speed and agility. His reflexes were also fast enough to caught an arrow fired at him by Yao Fei Gulong, a master archer.
- Master hand-to-hand combatant/Martial artist: Much like Slade Wilson, Billy was very skillful in unarmed combat. His skill was enough to rival Yao Fei, who was also a master hand-to-hand combatant/martial artist, and eventually subdue him in their second confrontation with aid from Fyers' mercenaries as well as contend against Slade himself for a while before he was beaten and killed. He also effortlessly defeated one of Fyers' prisoners and brutally beat the still untrained Oliver to the ground. In addition to unarmed combat, Billy is also well-versed in using acrobatics and high kicks in combat, which contrasted Slade's fighting style of a solid close-ranged fighting.
- Master swordsman: Billy used a sword as his primary weapon and was extremely proficient when using it. He could deflect an arrow with his sword. His skill with a sword was great enough to compete against Slade in a duel but was ultimately beaten.
- Master knife wielder: Billy is highly skilled at using a knife in combat. This seen during his fight with Slade, in which he used his combat knife along with his sword.
- Master marksman: As a former ASIS operative, Billy was an expert in the use of various firearms.
- Expert Strategist and tactican: Billy is skilled in military strategy and tactics. He was able to track down Yao Fei and Oliver Queen when they kidnapped Edward Fyers.
- Leadership: Billy was able to lead some soldiers to ambush Yao Fai and Oliver to resuce Edward Fyers.
- Expert interrogator/Torturer: Billy was a very skilled torturer, who was able to effectively gather information from his victims without harming them too much. Despite his skill, a relatively untrained and weak Oliver Queen was able to resist the torture to some degree, through Billy possibly held himself back in order to not kill him too fast.
- Suit: Billy used a variant of ASIS unit armor, as well as a distinctive orange-and-black balaclava, which was the same as his partner, Slade's.
- Curved sword: Like Slade, Billy used a curved grey sword as his primary weapon.
- Guns/Firearms: Billy used several different guns, including a pistol and a sub-machine gun.
- Combat Knife: Billy also utilized a combat knife which he holstered on his left leg. He used this in conjunction with his sword durimg his final fight with Slade.
- Smoke Grenade Cartridges: Billy carried three smoke grenade cartridges strapped to his armor.
- Billy Wintergreen gave Oliver Queen his second scar by cutting the lower left side of his abdomen with a sword.
- Billy was the godfather of Slade's son, Joe Wilson.
- Billy Wintergreen was the first character in the Arrowverse shown to be able to catch an arrow.
Behind the scenes
- In DC Comics, William Randolph Wintergreen is Slade Wilson's close friend and butler. He, too, was ultimately slain by Slade (despite being controlled by his son, Jericho).
- His costume and the fact that his eye is stabbed is a reference to Slade Wilson as Deathstroke. Billy was also referred to as "Deathstroke" in the credits of Arrow episodes.
- Billy Wintergreen never appeared without his balaclava during the show. His face was only shown in the tie-in comic books.
- A DC Collectibles action figure of Billy Wintergreen was released under the title "Deathstroke", even though he was never referred by this name on screen. However, the actor was credited as "Deathstroke" in the credits of multiple Arrow episodes.