Mylodon is a genus of extinct ground sloth belonging to the family Mylodontidae, known from the region of Patagonia in Chile and Argentina in southern South America. With a total length of 3 to 4 m, it is one of the best-known and largest representatives of the group. The oldest finds probably date to the Lower Pleistocene; however, most of the fossil remains date from the Upper Pleistocene period. One of the most important sites of this phase is the Cueva del Milodón in southern Chile. Shortly after, about 10,200 BP, Mylodon became extinct. At this point in time, it coexisted with the first human colonists in America. However, there is little evidence that it was hunted by humans.

In Mylodon's case, not only bones and teeth are known, but also various soft tissue and integumentary structures are preserved. The diet of Mylodon is known in great detail due to fossilized faeces. Its skull is greatly elongated and, compared to other large mylodontids, is narrower, possessing a completely closed nasal arch. Other distinguishing features concern the dental structure.

Mylodon was a terrestrial ground sloth. A thick coat with long hair can be interpreted as an adaptation to a life under cold climatic conditions, as they prevailed in southern South America during the last glacial period. A diet based predominantly on grasses also corresponds to this in this region. The widespread distribution of Mylodon into the pampas region and some features on the skull show, however, that the animals had a much larger ecological range and could also cope with warmer temperature conditions and possibly a mixed vegetable diet. Some of the animals fell victim to larger predators.

The genus was described in 1840, and only one species, Mylodon darwini is usually recognized. The type material comes from the area of the Pampas, where it was collected by Charles Darwin during his voyage with HMS Beagle. Mylodon was one of the first extinct sloths on which genetic studies were carried out.