As was already specified in this article, Lex Luthor made his first comic book appearance in April of 1940's Action Comics #23. Like a lot of comic books that mark specific events such as this, and a lot of comic books of that age in general, copies of that particular issue are worth a lot of money - especially if they're in good condition. In the case of Action Comics #23, a graded mint condition specimen can actually be worth up to $200,000, making any individual willing to sell their copy 1/5 of a millionaire instantly - not exactly Lex Luthor levels of richness, but still extremely rich. Even an ungraded copy in terrible condition can sell for $400, so it's well worth looking through your collection to see if you have it!
