The leader of the Klingon High Council who presided over that body longer than anyone else in history by using an iron hand to maintain peace within the council and the Empire itself.
One of K'mpec's greatest political challenges came in 2366, when evidence emerged implicating the late Ja'rod, father of council member Duras, of having committed treason. The politically powerful Duras attempted to suppress the fact that his father had betrayed his people to the Romulans at Khitomer. K'mpec feared that exposing Duras would plunge the Empire into civil war, so he gave tacit support to a plan whereby the late Mogh would be blamed for the massacre.
K'mpec did not realize that Mogh's sons, Worf and Kurn, would return to the Homeworld to challenge this injustice, an appeal that K'mpec was not willing to hear in open council.
K'mpec eventually agreed to allow Worf to accept discommendation, sparing both of Mogh's sons from death, while retaining some semblance of peace in the High Council. (Sins of the Father [TNG])
K'mpec was murdered in 2367, apparently poisoned with Veridium Six by Duras, who sought to succeed K'mpec as council leader.
Under Klingon custom, such a killing was without honor because the killer did not show his face to the victim.
Seeking to protect his empire from such a dishonorable person, K'mpec took the highly unorthodox step of appointing a non-Klingon, Jean-Luc Picard, as his Arbiter of Succession.
K'mpec was succeeded by Gowron, a political newcomer. (Reunion [TNG])
NOTES: Actor Charles Cooper also played General Koord in Star Trek V.