Nimon is a creepy leader of a race of retarded minotaurs who wanted to conquer Human colonies in the future. They used their powers of mind control to make people view them as Gods, only to be destroyed by a 'religious revolution'. Despite their defeats on the Human Colonies, Nimon and his minions decided that they were going to attack a Human starship instead, but unfortunatly for them the Doctor was there to stop them. Nimon and his pals were disintergrated in the destruction of the ship and the Humans escaped.
Nimon himself survived as a mass of essence however, and travelled the stars possessing people and getting them to do his bidding. He eventually rebuilt his body on a primitive world, but he couldn't leave the planet as he had no technology.