The long-serving leader of the Klingon High Council, who named Jean-Luc Picard Arbiter of Succession before his death.
K'mpec had led the Klingon High Council for many years. In Sins of the Father he knew that Duras's family had betrayed the colony at Khitomer to the Romulans, but he allowed Worf's late father Mogh to be blamed instead in order to protect the Empire from civil war. Worf accepted discommendation to keep that peace.
In Reunion, K'mpec was dying of slow poison. He asked Picard to serve as Arbiter of Succession and to find out which of the two candidates, Duras or Gowron, had poisoned him. He died soon afterwards, and the contest that followed led to Duras's death and eventually to the Klingon Civil War.