A mammoth is any species of the extinct elephantid genus Mammuthus, one of the many genera that make up the order of trunked mammals called proboscideans. The various species of mammoth were commonly equipped with long, curved tusks and, in northern species, a covering of long hair. They lived from the Pliocene epoch (from around 5 million years ago) into the Holocene at about 4,000 years ago, and various species existed in Africa, Europe, Asia, and North America. They were members of the family Elephantidae, which also contains the two genera of modern elephants and their ancestors. Mammoths are more closely related to living Asian elephants than African elephants.

The oldest mammoth representative, Mammuthus subplanifrons, appeared around five million years ago during the early Pliocene in what is now southern and eastern Africa. Later in the Pliocene, by about three million years ago, mammoths dispersed into Eurasia, continuing to propagate into numerous subsequent species, eventually covering most of Eurasia before migrating into North America around 1.5-1.3 million years ago, becoming ancestral to the Columbian mammoth (M. columbi). The last species to emerge, the woolly mammoth (M. primigenius), developed about 400,000 years ago in East Asia, with some surviving on Russia's Wrangel Island in the Arctic Ocean, as well as possibly the Taymyr Peninsula on mainland Siberia, until as recently as roughly 3,700 to 4,000 years ago, still extant during the construction of the Great Pyramid of ancient Egypt.