Commander Kruge was a male Klingon officer of the 23rd century Klingon Empire. In 2285, he commanded a Klingon Bird-of-Prey. He was romantically involved with Valkris and kept a Klingon monster dog as a pet.
In 2285, Kruge played a major role in a plot to obtain intelligence on the Genesis Device, a Federation technology designed to instantly terraform an entire planet. He saw it as an incredibly powerful weapon, and sought to bring that technology to the Empire. He recruited Valkris as a spy to obtain material from the project, and once successful, she made a rendezvous with Kruge on the Merchantman. When he learned from her that she had viewed the material even though she was not to have done so, however, he destroyed the vessel without beaming her aboard.
Kruge, now with the project summary in hand, ordered a course set for the Genesis Planet, which had only recently been formed. Arriving at that destination, he and his crew encountered the USS Grissom, a Federation science vessel assigned to study the planet. Kruge wanted to gain hostages with which to bargain for the Genesis technology, so he ordered his gunner to target the Grissom's engines in order to disable the vessel. However, in what the gunner described as a "lucky shot," the Grissom was destroyed. Kruge responded by instantly killing the gunner. After Torg found that a landing party from the Grissom had survived on the planet's surface, Kruge led a team to search for them.
Did You Know that James T. Kirk caused opponents with artificial intelligence to destroy themselves – using nothing but verbal arguments – on at least four separate occasions?