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. Superman: Secret Origin #1 (Nov. 2009)
depicts Kent celebrating his birthday on December 1.

... But don't let me stop you from being ignorant.

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