Kargh

Kargh was a Klingon, a member of the Klingon Defence Force and captain of the IKS Amar. In 2268 his vessel was assigned patrol of the Federation-Klingon border near quadrant L-14.

He died in 2272 when the V'Ger probe traversed Klingon space and destroyed the Amar and two of her sister ships.(ST:TMP).

The Doomsday War
In an alternate timeline where the USS Enterprise had been destroyed by a Doomsday Machine in 2254, the signing of the HoH'egh accord united the Federation and the Klingon Empire in a mutual self-preservation pact.Kargh was assigned as Science officer of the USS Farragut in 2264.

In 2268 the Farragut was sent to Gateway where they learned of the changes in the timeline. They used the Guardian of Forever to travel back through time and successfully corrected history, thus, Kargh never served on the starship. (STNV: "In Harm's Way").