Slade Wilson

Slade Wilson,codenamed Deathstroke by A.R.G.U.S., is a former member of the Australian Secret Intelligence Service and an ASIS unit, the secret mastermind behind the Church of Blood, which he used to recruit individuals for his army, and the mentor-turned-enemy of Oliver Queen. Slade is also the father of Joe Wilson, the potential father of Grant Wilson, and was also very close to Shado before her death, being secretly in love with her despite her affections for Oliver.

Slade was initially an ally of Oliver on the island, where he taught the shipwrecked playboy the majority of his combat skills (which he would later utilize in his crusade as the Arrow). Slade was later injected with an experimental Mirakuru serum after a near-fatal accident, and embarked on a crusade of vengeance against Anthony Ivo for killing Shado. Slade swore vengeance against Oliver as well upon learning that he chose to save Sara Lance over Shado, a woman he supposedly loved. During a climactic battle aboard the Amazo, Oliver presumably killed Slade after stabbing an arrow into his right eye. However, Slade survived and returned five years later as the mercenary "Deathstroke", with the intention of taking away everything and everyone Oliver held dear as vengeance for the events that transpired on Lian Yu. Working with Sebastian Blood and Isabel Rochev, Slade gathered an army and launched an all-out assault on Starling City, murdering Moira Queen in his blood lust. His plan ultimately failed, as he was cured of the Mirakuru and subsequently imprisoned in an A.R.G.U.S. facility back on Lian Yu.

However, in May 2017, Oliver visits Slade again on Lian Yu. Having long-since recovered from the mental-impairment of Mirakuru, he agreed to Oliver's requests to help in freeing his friends and combating Adrian Chase, all in the hopes of redemption and to find his lost son Joe.

In one potential timeline, Slade fathered a son named Grant Wilson, who would take up his father's mantle as Deathstroke.