Mumzillia O'Chubbacutch, also known as Mumzy, was an aging bankvole who lived by a river. She was the niece of Shaym, whom she apparently was fond of. She often quoted her uncle, and owned a few recipes and other items that formerly belonged to him.
Though she was a hermit, Mumzy always wanted children of her own. When she found Flib, Gurchen, and Guffy, she took them into her small dwelling and nursed Flib back to health with a special soup. She also took care of all of the young ones that escaped from Althier until it was safe for them to return to their families. When the oppression of the Sable Quean ended, she moved into Redwall Abbey to take care of the Dibbuns there.