The mountain beaver (Aplodontia rufa) is a North American rodent. Not to be confused with the North American beaverCastor canadensis, or its relative the Eurasian beaver, Castor fiber, it has several common names, including aplodontia, boomer, ground bear, and giant mole. The name sewellel beaver comes from sewellel or suwellel, the Chinookan term for a cloak made from its pelts. This species is the only living member of its genus, Aplodontia, and family, Aplodontiidae.