Pyro, Team Fortress 2
When backstory after backstory came for the Team Fortress 2 characters in the form of the Meet the Class series, the whole cast got fleshed out. Except for the Pyro, whose video was ultimately more confusing than illuminating. Speaking in mumbles, further muffled by their mask which has never been removed, the Pyro apparently sees the world in an explosion of rainbows and pink ponies—to this day, their gender along with their sanity, motives, and backstory remain largely a mystery.