| Named By: | Florentino Ameghino in 1887 |
| Time Period: | Early Miocene |
| Location: | South America |
| Size: | 2 meters long |
| Diet: | Herbivore |
| Fossil(s): | Several specimens |
| Classification: | | Chordata | Mammalia | Litopterna | Macraucheniidae | |
Theosodon is an extinct genus of litoptern mammal from the early Miocene of South America.
Theosodon bore a superficial resemblance the modern guanaco, and was around 2 metres (6.6 ft) in length, weighing up to 95.6 kg. It had a long neck and tapir-like, three-toed feet. Judging from the position of its nostrils, Theosodon had a short trunk, though shorter than its other relatives, such as Macrauchenia.
Theosodon had a full set of 44 teeth, and its lower mandible was very thin and large.