Kruge was the ruthless commander of a Klingon Bird of Prey, a scout class vessel in the Klingon fleet. He became obsessed with the Genesis device, which had the ability to transform lifeless moons or planets into habitable worlds. Although it was originally designed to be a means for colonization, Kruge was only interested in it's destructive power and he was willing to go to any lengths to get it.Sometime after the the creation of the Genesis planet, Kruge's lover, Valkris, got a hold of Admiral James Kirk's report on Genesis. The spy used a freighter to rendezvous with Kruge's ship and give him the report. She also revealed that she saw it, although she apparently wasn't supposed to. Both Kruge and Valkris understand this means she had to die, so Kruge's ship destroyed the freighter with her on it. The commander ordered his ship to head for the Federation neutral zone.While they are en route to Genesis, Kruge showed the report to two of his men, Torg and Maltz. Torg's reaction pleased Kruge, but Maltz's did not. Kruge secretly told Torg that he planed to cross into Federation space and steal the secret of Genesis from the planet itself.The Bird of Prey's cloaking device allowed the Klingons to remain hidden until they decided to attack the Federation ship USS Grissom at the Genesis planet. Despite Kruge's order to disable the ship, the Klingon attack destroyed the Grissom. Furious, Kruge executed his gunner on the spot. However, he calmed down when Torg discovered life signs on the planet.Kruge transported to the surface with two soldiers. He found a large worm-like creature and strangled it. The following morning, Kruge captured Lieutenant Saavik, David Marcus, and a Vulcan boy. (Kruge was unaware that David is Admiral Kirk's son or that the boy is a regenerated Spock.) Kruge's interrogation of his captives was interrupted by the arrival of the USS Enterprise. Kruge beamed back to his ship.The Enterprise, under Kirk's command, slowly closed in on Genesis. The admiral stole his old ship and, with the help of his friends, came to Genesis to help Spock. Kruge planed to let them get close enough and then attack them. However, the Bird of Prey had to drop the cloak and become visible before the Klingons could fire. Kruge made sure his new gunner understood that only the engines were to be targeted. Unfortunately for the Klingons, Kirk and his crew spotted a distortion in space which was Kruge's hidden ship. When the Bird of Prey decloaked, Enterprise fired two torpedoes which damaged the Klingon ship. The Klingons returned fire and crippled Enterprise.Kirk tried to bluff Kruge into surrendering, but the Klingon sensed that he was lying. Kruge told his enemy that he had three prisoners on the planet who will be killed if Kirk didn't give up. Kirk was allowed to speak to Saavik and David, who told him about the Vulcan boy. They also informed Kirk that the planet was unstable and about to destroy itself within hours. David told Kirk not to surrender, citing his belief that the Klingons wouldn't kill them over a failed project. Kruge reacts to this by ordering his men to kill one of the prisoners. Although Saavik is selected for death, David attacked her would-be killer and was killed instead. David's death caused Kirk to break down emotionally and curse the Klingons. Unmoved, Kruge repeated his demand for surrender. Kirk agrees, but asked for time to tell his crew.Kruge ordered Torg to form an armed boarding party to take control of Enterprise. The Klingons beamed aboard the ship, but found it deserted. Torg contacted Kruge and told him the computer was performing a mysterious countdown. Realizing he had been tricked, Kruge tried to warn his men to get off the ship, but it was too late. The Enterprise self-destructed, taking Torg and the boarding party with it.With his head buried in his arms, Kruge suddenly got a call from the planet's surface. It was Kirk, who told him that he had the secret of Genesis. Instead of beaming them up, Kruge beamed himself down to the planet and held Kirk's party at bay with his disruptor pistol. He ordered Maltz to bean up everyone except himself, Kirk and Spock, who had collapsed into a coma. Kruge demanded the secret of Genesis, while Kirk requested that he beam Spock to his ship. The two commanders got into a fight, while the planet deteriated around them. A ledge gave way under Kruge, leaving him hanging on to the edge. Kirk offered Kruge his hand, but the Klingon grabed his foot and tried to drag him over the edge. Realizing that reasoning with Kruge was out of the question, Kirk declared he'd had enough of him and kicks the Klingon to his death in a sea of lava below them.Although he was killed, Kruge's actions would continue to haunt Kirk. The death of David left the admiral with a bias towards Klingons that he would carry with him for many years. Show less «