A Zeon living on Ekos who works with the underground and helps Kirk and Spock reach John Gill.
Isak is a member of the Zeon community living on Ekos, where Zeons are persecuted under the Nazi-style regime. In Patterns of Force he is part of the underground resistance, and he helps shelter Kirk and Spock after they escape from captivity.
Isak joins the infiltration of the Führer's headquarters and is present when John Gill denounces Melakon. When Melakon shoots Gill, Isak kills Melakon. At the end of the episode, he and the Ekosian Daras look toward rebuilding relations between their peoples. He was played by Richard Evans.