Stonefleck was a large, grey rat, who was the leader of the Longtail Horde, a group of rats allied with Malkariss and Slagar the Cruel that assisted the latter in crossing the Southern Plateau river. He was impassive, only speaking when he absolutely had to, and even then, he would speak in a flat voice (almost completely monotone in the TV Series).
When his army tried to stop Matthias and his companions, Stonefleck was killed by Log-a-Log. As Stonefleck saw that his army was losing the battle against Matthias' friends, he tried to sneak away unnoticed; however, Log-a-log spotted the rat and threw his rapier at him, spearing Stonefleck through the back.