The elk (Cervus canadensis), or wapiti, is one of the largest species within the deer family, Cervidae, and one of the largest terrestrial mammals in its native range of North America and Central and East Asia. The word "elk" originally referred to the European variety of the moose, Alces alces, but was transferred to Cervus canadensis by North American colonists. The name "wapiti", derived from a Shawnee and Cree word meaning "white rump", is also used for C. canadensis.

Elk range in forest and forest-edge habitat, feeding on grasses, plants, leaves, and bark. Male elk have large antlers which they shed each year. Males also engage in ritualized mating behaviors during the rut, including posturing, antler wrestling (sparring), and bugling, a loud series of vocalizations that establishes dominance over other males and attracts females. Although it is currently native to North America and central/eastern Asia, it had a much wider distribution in the past. Populations were present across Eurasia into Western Europe during the Late Pleistocene and survived into the early Holocene in southern Sweden and the Alps; the extinct Merriam's elk subspecies ranged into Mexico. The elk has adapted well to countries where it has been introduced, including Argentina and New Zealand. Its adaptability may in fact threaten endemic species and the ecosystems into which it has been introduced.

Elk are susceptible to a number of infectious diseases, some of which can be transmitted to livestock. Efforts to eliminate infectious diseases from elk populations, largely by vaccination, have had mixed success. Some cultures revere the elk as having spiritual significance. In parts of Asia, antlers and their velvet are used in traditional medicines. Elk are hunted as a game species. Their meat is leaner and higher in protein than beef or chicken. Elk were long believed to belong to a subspecies of the European red deer (Cervus elaphus), but evidence from many mitochondrial DNA genetic studies beginning in 1998 shows that the two are distinct species. Key morphological differences that distinguish C. canadensis from C. elaphus are the former's wider rump patch and paler-hued antlers.