Reptile refers to the lizard-like creatures of UO. There are traditional reptiles, like snakes and alligators, races of reptiles, such as Lizardmen, Ophidians, and the Dragon family of creatures, and named reptiles, like Abscess, Grim, and Thrasher. Lizardmen have been seen since the first Ultima and were magically created by Mondain the deceiver.

As a group, they are vulnerable to the Reptile Super Slayer, while certain reptiles are susceptible to specific Lesser Slayers.