An Enterprise lieutenant and geophysicist who beams down to the rogue planet Gothos in 2267 to search for Kirk and Sulu and becomes a plaything of Trelane.
Lieutenant Karl Jaeger appears in the first-season episode The Squire of Gothos. After Kirk and Sulu vanish from the bridge, Spock sends him to the surface with DeSalle and McCoy. In the middle of a poisonous wasteland they find a pocket of breathable air and an eighteenth-century manor house.
Their host, Trelane, is delighted by Jaeger's name and greets him as a German soldier, barking out a few marching steps. Jaeger answers stiffly that he is a scientist.
He notices that the fire in the hearth gives off no heat, one of the first signs that Trelane has copied Earth without understanding it. He is beamed up with the others when Spock locks on to every life form in the area. Jaeger was played by Richard Carlyle.