Grevaq

Councillor Grevak was a Klingon who served in the Klingon High Council as of 2379 when he was still a young warrior. That year, Worf had a meeting with the Council regarding the upcoming election for Federation President. Grevak attempted to ask Worf if the Federation was responsible for replacing Emperor Kahless with a hologram, but he was chastisted by Chancellor Martok for attempting to speak for him.

Some time soon after this, Alexander Rozhenko, acting on behalf of the Federation, met with Grevak and was able to convince him to pledge his continued support for the Klingon-Federation alliance. (TNG novel: A Time for War, A Time for Peace)