The fancy rat is a domesticated brown rat (Rattus norvegicus), which is the most common type of pet rat. The name fancy rat derives from the idea of animal fancy or the phrase "to fancy" (to like, or appreciate).Fancy rats have their origins as the targets for blood sport in 18th- and 19th-century Europe. Specially bred as pets since then, fancy rats now come in a wide variety of colors and coat types and there exists several rat fancier groups worldwide.