Hellboy is a fictional character created by writer-artist Mike Mignola. The character first appeared in San Diego Comic-Con Comics 2, and has since appeared in various eponymous miniseries, one-shots and intercompany crossovers.
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.
