Mastodons (Greek: μαστός "breast" and ὀδούς, "tooth") are an extinct group of mammal species related to elephants, that inhabited North and Central America during the late Miocene or late Pliocene up to their extinction at the end of the Pleistocene 10,000 to 11,000 years ago. Their genus name is Mammut, and they are members of the order Proboscidea. They lived in herds and were predominantly forest dwelling animals that fed on a mixed diet of browsing and grazing with a seasonal preference for browsing, in contrast to living elephants that are mostly grazing animals.

The American mastodon is the most recent and best-known species of the genus. They disappeared from North America as part of a mass extinction of most of the Pleistocene megafauna, widely presumed to have been a result of rapid climate change in North America, as well as the sophistication of stone tool weaponry used by the Clovis hunters which may have caused a gradual attrition of the mastodon population.