Not much is known of Sheridan the Time Sheep as he does not speak the common tongue of dudes, and is also a sheep. At random intervals the black shaggy bleating beast will disappear and reappear, at no control of its own. While it cannot speak, sometimes it manages to write a message or draw a picture with its hooves before a spasm takes over and sends it out of the world once more, and it is from this scholars have gathered the ovine timelord's name as well as some brief and spotty knowledge on the the subject of a world that exists parallel or came before the once we occupy. Scholars of the ancient world suspect he may be a doomsayer prophet of the old world with the ability to travel through time back and forth between moons neither here or now, but how, why, and where it goes are hazy guesses at best. For whatever the reason is that drives dudes to kill things unkown to them, some have made the attempt, and end up as bloody piles at Sheridan's hoofs.
Sheridan is bipedal and stands taller than the average dude. Some claim he must be a member of the Skeniks cast of beastial people-things.
Because of the other-wordly protection he's got, you can't kill that guy, so he's in the ranks of the Unkillables. Or her. Whatever, just keep that smelly black mange and its doomsday nay-saying away from the brigand party.