Superman's age has varied through his history in comics. His age was originally left undefined, with real-time references to specific years sometimes given to past events in Golden Age and early Silver Age comics. In comics published between the early 1970s and early 1990s, his age was usually cited as 29 years old. However, during "The Death of Superman" storyline, Clark's age was given as 34 years old (in a fictional promotional newspaper published), while 1994's "Zero Hour" timeline established his age as 35.

Action Comics #149 (Oct. 1950) gives October as Superman's birthdate. Comics of the 1960s through 1980s describe Superman's birthday as February 29. Clark Kent, meanwhile, would celebrate his birthday on June 18, the date the Kents first found Clark; June 18 is also the birthdate of Superman voice actor Bud Collyer. Following the 1980s editorial-revamp DC called Crisis on Infinite Earths, Kent's birthday is given as February 29.

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