Hugo Lang

Lieutenant Hugo Lang was an officer in the A Squadron of the Interplanetary Pursuit. He was sent to find the abductors of Romulus and Remus Sylvest, but was shot down over Titan III and crashed. He was rescued by the Sixth Doctor and travelled with him to Jaconda, where he helped him defeat Mestor.

Afterwards, as he had no family and nothing to go back to Earth for, he decided to stay and help the Jacondans rebuild their world. The Doctor handed him Azmael's ring. (TV: The Twin Dilemma)