Grunnil was a male Klingon, and the head of the House of Grunnil. Grunnil held many antiquated views regarding the roles of females in Klingon society, which he taught to the young males of his House, including Lokor and Vralk. (TNG - The Brave and the Bold, Book Two novella: The Final Artifact)

As Lokor and Vralk are identified as cousins, Grunnil is likely the grandfather of both.