Mousefur is a small, wiry, thick, glossy, and soft-furred dusky brown she-cat with blue eyes.

Mousefur was a Thunderclan elder who served as a warrior under Bluestar's and Firestar's leaderships in the forest and the lake territories. She was born to One-eye and Halftail as Mousekit alongside her brother, Runningkit. She was later apprenticed as Mousepaw with Redtail as her mentor. As a young warrior, Mousefur participated in a Sunningrocks skirmish. She continued to fight for her Clan against Brockenstar, all the while training her first apprentice, Thornpaw. Her brother was later killed by Tigerclaw and his rogues.