Arrow: 8 Best Villains

Prometheus and Adrian Chase entered the scene at the beginning of Arrow's fifth season, the former a violent serial killer with a vendetta against Oliver Queen and his vigilante persona, the latter a likable district attorney who became a friend and ally to Oliver, and the eventual reveal that the two were one in the same was a standout moment of the season.

His motivations were a bit undercooked - he was attempting to destroy Oliver's life over his father's death at the hands of the Hood - and his final action of destroying Lian Yu with Oliver's friends and family on it was undermined by the sixth season revelation that all but one managed to survive, but that doesn't take away from the fact that Prometheus was an awesome villain. Actor Josh Segarra did an excellent job with the character, stealing every scene he was in, particularly once Chase's status as Prometheus was revealed.

Unlike many of the major villains, too, Chase was willing to go all the way in what he was willing to give up in order to "beat" Ollie, both killing his own wife to keep her from turning him in once she was clued in to who he really was and even himself to ensure Lian Yu's destruction. Throw in a cool costume, a cool voice, and a slick musical theme and Prometheus easily cemented himself as one of the show's most unforgettable threats.