| Named By: | Ameghino in 1891 |
| Time Period: | Miocene |
| Location: | Argentina - Santa Cruz Formation |
| Size: | Unavailable |
| Diet: | Omnivore |
| Fossil(s): | Partial remains |
| Classification: | | Chordata | Aves | Rheiformes | Rheidae | |
Opisthodactylus is an extinct genus of rhea from the Miocene of Argentina. Two species are known: the type species, Opisthodactylus patagonicus, and Opisthodactylus horacioperezi.