Rovus

 was a Star Man. It possessed Ensign Renn, a member of Kala Trace's crew. He was the leader of his race. Part of him in the Larger Magellanic Cloud kidnapped Tegan Jovanka, to attract the human ship and the Fifth Doctor. He also tried to possess Adric but couldn't because of Adric using maths to occupy his mind. He came from an alternative reality and his existence was changing human history. He told the Doctor about how his race came to this universe. He died when Adric closed the rift and destroyed the Keltin core. (AUDIO: The Star Men)