First: A human druid named Jon in a 1st Edition AD&D game. My cousins computer generated a dozen PCs and we got to choose; Jon had the least-sucky stats. (I later found out they generated the ability scores by having the computer randomly come up with a number between 3 and 18 instead of adding three numbers between 1 and 6, so it's no wonder the stats all had several lousy ability scores.) I played him once in a game designed to introduce my two brothers and me to AD&D, and we were hooked.
Most recent: A human sorcerer named Alistair Mandelberen Pastlethwaite, youngest son of a minor noble family who got kicked out when his sorcerous abilities started manifesting, as his father determined Alistair must have been trafficking with demons to learn to cast spells. Poor Alistair had no idea he was even casting spells; he just assumed his unseen servant was Ogilvy, the ghost of a butler the family employed when he was a little boy and who must have come back to see to Alistair's needs. All of his starting spells known were comfort related, but he had training with the rapier and thus made a living as an adventurer that way until he came to learn how sorcerers worked (and that he actually was one). He kept shooing away "that annoying grackle" until the other PCs explained the bird was his familiar.
Strangest: Probably the gestalt humanoid crow ranger/rogue named Sam Crow in a D&D 3.5 game my son retrofitted into a playable Skylanders campaign to introduce my 10-year-old nephew (a big Skylanders fan) to TTRPGs. Sam was a coward (his "battle cries" were "Let's get out of here!" and "Help me, Baabby, help me!" - Baabby was my nephew's PC, a gestalt humanoid sheep cleric/baabarian) and a member of the Sons of Archery. His proudest moment was when he "dropped trou" and took a dump on an Elder God's eye.
Johnathan