Kirk's friend, who gains godlike powers after encountering the galactic barrier.
Gary Mitchell is a lieutenant commander and helmsman aboard the USS Enterprise in Where No Man Has Gone Before, the original series' second pilot, played by Gary Lockwood. He is one of James T. Kirk's oldest friends, having known him since Starfleet Academy, and he is charming, confident and popular with the crew.
When the Enterprise tries to cross the energy barrier at the edge of the galaxy, Mitchell and the psychiatrist Elizabeth Dehner are struck by it and begin to develop immense psychic powers. Mitchell's abilities grow rapidly, his eyes turn silver, and he comes to see ordinary humans as beneath him. Spock urges Kirk to kill him before it is too late.
Kirk tries to maroon him on the remote planet Delta Vega, but Mitchell breaks free. Dehner turns against him, and Kirk kills him in a final confrontation. The episode explores how power can corrupt even a trusted friend.