 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).