How is Superman's birthday February 29 [Supes actually has a "few" birthdays, more on that later]? Back in the Silver Age, it was established by Editor Julie Schwartz that Superman's birthday was on February 29 and that was the reason why he stayed so young looking.
In 1985's Superman Annual #11 his birthday is officially mentioned as being February 29 in the actual pages of the story and a whole article was dedicated to Superman's February 29th birthday in the 1988 issue of TIME Magazine.
Of course, for strange reasons, "Clark Kent" celebrates his birthday on June 18th as established in the 1958 issue of Action Comics #241. And while other writers have attempted over the years to make Superman's birthday fall on a different date, February 29th is the date that fans usually chose to celebrate. Arguably and as a product of DC's long maligned continuity issues , he has a "couple" of birthdays but today happens to be one of them and so we'll celebrate.
Regardless, whatever you do, don't get Supes the same gift that Mongul got him or be prepared to suffer the consequences!
Superman is a fictional comic book superhero appearing in publications by DC Comics, widely considered to be an American cultural icon. Created by American writer Jerry Siegel and Canadian-born American artist Joe Shuster in 1932 while both were living in Cleveland, Ohio, and sold to Detective Comics, Inc. (later DC Comics) in 1938, the character first appeared in Action Comics #1 (June 1938) and subsequently appeared in various radio serials, television programs, films, newspaper strips, and video games. With the success of his adventures, Superman helped to create the superhero genre and establish its primacy within the American comic book. The character's appearance is distinctive and iconic: a blue, red and yellow costume, complete with cape, with a stylized "S" shield on his chest. This shield is now typically used across media to symbolize the character.
The original story of Superman relates that he was born Kal-El on the planet Krypton, before being rocketed to Earth as an infant by his scientist father Jor-El, moments before Krypton's destruction. Discovered and adopted by a Kansas farmer and his wife, the child is raised as Clark Kent and imbued with a strong moral compass. Very early he started to display superhuman abilities, which upon reaching maturity he resolved to use for the benefit of humanity.
Superman has fascinated scholars, with cultural theorists, commentators, and critics alike exploring the character's impact and role in the United States and the rest of the world.