Limnoria lignorum, commonly known as the gribble, is a species of isopod in the family Limnoriidae. It is found in shallow water in the North Atlantic and North Pacific Ocean where it tunnels into wood and attacks and destroys submerged wooden structures.

A gribble /ˈgɹɪbəl/ is any of about 56 species of marine isopod from the family Limnoriidae. They are mostly pale white and small crustaceans, although Limnoria stephenseni from subantarctic waters can reach 10 mm (0.4 in).