Marhari was the leader of the Northmen during the Battle of the Plains in which he was slain while fighting as the rearguard. By the valiance of Marhari and his men, the armies of Gondor were saved and could make their escape.

He was a descendent of Vidugavia, the self-proclaimed King of Rhovanion. The title of Lord of the Éothéod was passed to his son, Marhwini.