Grannk was a male Klingon who served as a captain in the Klingon Defense Force in the late 24th century.

Sometime prior to 2376, Grannk underwent an operation performed by Dr. Tiklor, which was observed by Dr. B'Oraq. According to B'Oraq, Tiklor bungled the surgery and nearly killed Grannk. (KE novel: A Burning House)