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Antagonists

The villains Superman faced in the earliest stories were ordinary humans, such as gangsters, corrupt politicians, and violent husbands; but they soon grew more colorful and outlandish so as to avoid offending censors or scaring children. The mad scientist Ultra-Humanite, introduced in Action Comics #13 (June 1939), was Superman's first recurring villain. Superman's best-known nemesis, Lex Luthor, was introduced in Action Comics #23 (April 1940) and has been depicted as either a mad scientist or a wealthy businessman (sometimes both). In 1944, the magical imp Mister Mxyzptlk, Superman's first recurring super-powered adversary, was introduced. Superman's first alien villain, Brainiac, debuted in Action Comics #242 (July 1958). The monstrous Doomsday, introduced in Superman: The Man of Steel #17–18 (Nov.-Dec. 1992), was the first villain to evidently kill Superman in physical combat without exploiting Superman's critical weaknesses such as kryptonite and magic.