Odocoileus is a genus of medium-sized deer (family Cervidae) containing three species native to the Americas. The name, sometimes spelled odocoeleus, is a contraction of the Greek root odont-, meaning "tooth," and -coelus, New Latin for "hollow".

The genus Odocoileus was named by French zoologist, Constantine S. Rafinesque, in 1832, based on teeth and part of a jaw (presumably of Odocoileus virginianus) gathered by a Mr. Wardel from an anonymous cave in Carlisle, Pennsylvania on the banks of the Conococheague Creek, and kept in the collection of a Mr. Hayden of Baltimore. Rafinesque could refer these teeth to no other living animal known to him, despite having then lived in native white-tailed deer habitat for decades (although the white-tailed deer had been previously described in the literature, between 1850 and 1900 the white-tailed deer population was reduced to 300,000 to 500,000 individuals, found only in remote locations inaccessible to humans). Rafinesque described enamel that covered the tooth, including the hollow inside, and named the species Odocoileus speleus, for "teeth well hollowed" and speleus referring to a cave.