Krell was the Klingon responsible for upsetting the balance of power, in 2267, within the culture on Tyree's planet by providing a rival clan of villagers led by Apella with the advanced technology of flintlock weapons. He promised Apella that if he cooperated with the Klingons, he would be given power over the planet. In turn, Krell would be able to establish a puppet government with alliance to the Klingon Empire. Krell's mission was foiled when James T. Kirk discovered the plot and armed Tyree's clan with the same weapons.As a product of 22nd century genetic engineering, Krell was descended from Klingons affected with the augment virus created in 2154, and thus had a more human-like appearance than normal Klingons. He also displays an almost Ferengi-like interest in motivating troops through profit, rather than honor, in his discussion with Apella.