The Spectre
Another morally ambiguous character, The Spectre is a force that needs a human host so it can reek vengeance on those who have murdered. At one point, The Specter is taken up by Hal Jordan’s spirit, which could also be an interesting aspect to focus on. Darker than the rest of The CW Arrowverse, it would be cool to see what this character could add. His brutal judgements of human crimes is also perfect for a serialized TV show.