| Named By: | Georges Cuvier in 1804 |
| Time Period: | Early to Middle Eocene |
| Location: | Europe, including France, Germany, Spain, Switzerland and the United Kingdom |
| Size: | About 120 centimetres long, 75 to 140 centimetres high at the shoulder. Measurements vary between species |
| Diet: | Herbivore |
| Fossil(s): | Multiple individuals |
| Classification: | | Chordata | Mammalia | Perissodactyla | Palaeotheriidae | |
Palaeotherium ('old beast') is an extinct genus of primitive perissodactyl ungulate. George Cuvier originally described them as being a kind of tapir, and as such, Palaeotherium is popularly reconstructed as a tapir-like animal. Recent reexaminations of the skulls show that the nasal cavity was not shaped to support a small trunk, thus starting a recent trend to reconstruct them as looking more horse-like. Recent anatomical studies also suggest that Palaeotherium, along with other palaeothere genera such as Hyracotherium, were closely related to horses.
The average species of Palaeotherium was about 75 cm (2 ft 6 in) tall at the shoulder and lived in the tropical forests covering Europe around 45 million years ago, during the early to mid Eocene. The largest species, P. magnum of Mid Eocene France, grew to be almost as large as a horse.