Hermey the Misfit Elf (now named Hermey the Elf, D.D.S) is one of Santa Claus' elves, and the deuteragonist in the 1964 television special Rudolph the Red-Nosed Reindeer and its 2001 sequel Rudolph the Red-Nosed Reindeer and the Island of Misfit Toys.
Vote which fictional character would naturally fit in-universe with a big-named franchise! No time-travel, no interdimensional crap, no "Pooh's Adventures", they would just exist in-universe.