Fan Casting Dr. Hugo Strange in The Batman (1990)

Dr. Hugo Strange is the true main antagonist of The Batman. A well-respected scientist and biologist as well as the chief psychologist of Arkham Asylum and former friend of both Thomas Wayne and Leslie Thompkins, with him acting as a father-figure to Bruce after his parents death. He's also the boss of Jack Napier, later known as the Joker, who treated the latter as a child and thus is responsible for moulding him into the monster he became as an adult, as well as one of the few to find out Batman's true identity earlier on. He, alongside the Joker, wants to use the latter's Smilex gas to bring death to all the citizens of Gotham, of whom he views as scum, in order to take over the city and then sell the weaponized gas to the highest bidder.