Mister Miracle (Scott Free) is a fictional superhero appearing in American comic books published by DC Comics. He first appeared in Mister Miracle #1 (April 1971) and was created by Jack Kirby.
This is going off the debut of comic book characters. In the cases of characters who were introduced in other media originally and added to the comics canon later along (ex: Harley Quinn) it'll go by actual debut year.