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 North America and Northeast Asia. This animal should not be confused with the still larger moose (Alces alces) of North America, alternatively known as "elk" in British English and related names in other European languages (German Elch, Swedish älg, French élan), in reference to populations in Eurasia. Elk range in forest and forest-edge habitat, feeding on grasses, plants, leaves, and bark. Male elk have large antlers which are 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 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 elk has adapted well in 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.