Mammoths are large proboscideans (elephant-like animals) that lived during the Pleistocene, Pliocene, and early Holocene epochs — 4.8 million to around 4,500 years ago. They were probably made extinct by humans. Mammoths are all members of the genus Mammuthus. Mammoths were herbivorous, like their living relatives the elephants, and would have consumed around 250 kg (550 lb) of fresh vegetable matter a day, which would have been difficult in glacier-covered Eurasia.

Mammoths had long, shaggy hair to help them survive the Ice Age environment, along with massive tusks, used for defense from predators such as predatory felines, canids, and humans. Mammoths were part of a larger trend in evolution in the Ice Age which favored larger animals. These animals are called the megafauna, and most went extinct when their habitats changed and they became susceptible to hunting by humans.

At least eleven species of mammoth are recognized: Mammuthus columbi (Columbian mammoth), Mammuthus primigenius (Woolly mammoth), Mammuthus subplanifrons (South African mammoth), Mammuthus exilis (Pygmy mammoth), Mammuthus imperator (Imperial mammoth), Mammuthus africanavus (African mammoth), Mammuthus trogontherii (Steppe mammoth), Mammuthus meridionalis (Southern mammoth), Mammuthus lamarmorae (Sardinian dwarf mammoth), Mammuthus jeffersonii (Jeffersonian mammoth), and Mammuthus sungari (Songhua River mammoth).

Despite the modern meaning of the word "mammoth" as an adjective, mammoths were not much larger than today's elephants. Although the largest known species, the Imperial Mammoth of California, exceeded 5 meters (16 feet) in height, weighing as much as 13 tons, most mammoths were smaller, not much larger than a modern Asian Elephant. There were even three species of dwarf mammoths, all examples of island gigantism: the Pygmy Mammoth, which lived on the California Channel Islands, which themselves are less than 200 sq mi in area, the Sardinian Mammoth, found on the Mediterranean island of Sardinia, and the Wrangel Island Mammoth, from an island north of Siberia and within the Arctic Circle, the only known dwarf woolly mammoth.