Aegialomys galapagoensis (Waterhouse, 1839) is a sigmodontine rodent commonly called the Galapagos rice rat. It is a medium-sized rodent, characterized by dense, soft, yellow or copper, weakly grizzled pelage; the dorsum is grayish or brownish and the ventral pelage is pale. It is endemic to the open habitats of the Galapagos Archipelago, occurring on three islands, Santa Fé Island (Barrington Island), San Cristóbal Island (Chatham Island), and Santiago Island (James Island). Restricted populations are considered a major threat to A. galapagoensis conservation throughout most of its range, as well as competition with Rattus rattus. A. galapagoensis is listed as “Vulnerable” by the International Union for Conservation of Nature and Natural Resources, and is listed as “Critically Endangered” on the Ecuador National list.