A Mad Tinkerer the group first encounters in the Lodestar in the sky, in Episode 4:Ride the Lightning. He is a short little Gnomish man with a bald head. He wears tiny spectacles on the end of his nose that look like they have multiple layers to them. He's got short squat little legs and he is wearing a wool coat.
On the top floor of the Lodestar there were 3 clones of him. His clones were not bothered by the lightning.