- For other uses, see Krell.
In 2267, Krell was dispatched to the planet Neural on a mission to upset the balance of power against tribal leader Tyree, by supplying one of his rivals with the "advanced technology" of flintlock weapons. Krell eventually gained the support of Apella after Krell promised him that if he cooperated with the Klingons, then he would become leader of the planet, and in turn, Krell would establish a puppet government and form an alliance with the Klingon Empire. Unfortunately, Krell's plot was later foiled by Captain James T. Kirk and the crew of the USS Enterprise who supplied Tyree's tribe with similar weaponry. (TOS episode & novelization: A Private Little War; WizKids module: Attack Wing)
By the early 2270s, Krell had risen to the rank of commander and served as commanding officer of a K't'inga-class battle cruiser. In 2273, Krell was ordered to proceed to Earth accompanied by two additional battle cruisers, the IKS Ravager and IKS Deathcry, and meet with the Federation Council and receive a detailed account about the destruction of the IKS Amar and two other cruisers during the V'Ger crisis.
En route, Krell's cruiser detected the newly refitted USS Enterprise warping out of the Sol system. Realizing the potential advanced technologies incorporated into the starship, Krell ordered his ships to pursue the Enterprise to the Scylla sector, where they ambushed the Constitution-class vessel and ordered Captain Kirk to surrender his ship. Unfortunately, Krell was forced to abandon the assault when the Enterprise tested the "omegatron device" on his ship and crippled her. (TOS - Untold Voyages comic: "Renewal")
- The Krell who appeared in TOS - Untold Voyages comic: "Renewal" wasn't associated with the Krell who appeared in TOS episode: "A Private Little War", but with no contradictory evidence, it has been assumed that they are the same person. The fact that Krell had cranial ridges in "Renewal" could be resolved by the fact that, like many QuchHa' Klingons, the cure that was developed in the 2270s was successful on him or he had ridges surgically added, as revealed in ST novel: Excelsior: Forged in Fire.
By the year 2287 Krell had risen to the rank of General and placed in a position with Operations Command in the Klingon Defense Force. When the Galactic Army of Light terrorist group took the Klingon Diplomat Korrd hostage on Nimbus III, Krell ordered the IKS Okrona to free the hostages. Captain Klaa, the Commanding Officer of the Okrona, wondered why Operations Command would suddenly be worried about Korrd and Nimbus III. Klaa's Executive Officer, Vixis, recalled that Korrd's sister was married to General Krell. (TOS novelization: Star Trek V: The Final Frontier)