Santa Claus is based on an actual guy. He’d be Nikólaos of Myra, whom we also know as St. Nicolas. His feast day is today, in honor of his death on 6 December 343.
While a lot of people know about the Santa Claus mythology—whether it comes from Clement Moore’s poem, the Rankin-Bass animated specials, or the various movies which play with the Santa story—they tend to know little to nothing about the person at the back of it all. So let me rectify that.