A grishnar cat is an animal, presumably native to Qo'noS, considered to be weak and harmless, despite its fearsome appearance and roar.

Chancellor Gowron compared Captain Benjamin Sisko to a "toothless old grishnar cat" when he boasted of Deep Space Nine's upgraded defensive systems in 2372, as the conflict between the Klingon Empire and the Federation over the invasion of Cardassia came to a head. (DS9 episode: "The Way of the Warrior")

Lieutenant Vall of the IKS Gorkon earned the nickname "Grishnar" from his fellow officers for his non-warrior-like demeanor. (TNG novel: Diplomatic Implausibility)