that Lois discover that Clark is Superman because he felt that, as implausible as Clark's disguise is, the love triangle was too important to the book's appeal. However, Siegel wrote stories in which Lois suspects Clark is Superman and tries to prove it, with Superman always duping her in the end; the first such story was in Superman #17 (July–August 1942). This was a common plot in comic book stories prior to the 1970s. In a story in Action Comics #484 (June 1978), Clark Kent admits to Lois that he is Superman, and they marry. This was the first story in which Superman and Lois marry that wasn't an "imaginary tale." Many Superman stories since then have depicted Superman and Lois as a married couple, but about as many depict them in the classic love triangle. In modern era comic books, Superman and Lois are a stable married couple, and the Superman supporting cast was further expanded with the introduction of their son, Jonathan Kent. Other supporting characters include Jimmy Olsen, a photographer at the Daily Planet, who is friends with both Superman and Clark Kent, though in most stories he doesn't know that Clark is Superman. Jimmy is frequently described as "Superman's pal", and was conceived to give young male readers a relatable character through which they could fantasize being friends with Superman. In the earliest comic book stories, Clark Kent's employer is George Taylor of The Daily Star, but the second episode of the radio serial changed this to Perry White of the Daily Planet. Clark Kent's foster parents are Ma and Pa Kent. In many stories, one or both of them have died by the time Clark becomes Superman. Clark's parents taught him that he should use his abilities for altruistic means, but that he should also find some way to safeguard his private life. 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