| Named By: | A. S. Romer in 1937 |
| Time Period: | Early Permian,[1] Artinskian |
| Location: | USA, Texas - Belle Plains Formation |
| Size: | Skull 5.7 centimetres long, total body length estimated about 30 centimetres long |
| Diet: | Insectivore |
| Fossil(s): | Skull |
| Classification: | | Chordata | Synapsida | Pelycosauria | Caseasauria | Eothyrididae | |
Eothyris is an extinct genus of the family Eothyrididae. It was an insectivorous synapsid. It was closely related to Oedaleops. Only the skull of Eothyris, first described in 1937, is known. It had a 6 centimetres (2.4 inches) long skull, and its total estimated length is 30 centimetres (12 inches).