Thecachampsa is an extinct genus of tomistomine crocodylian. Fossils have been found from the eastern United States in deposits that are between late Oligocene and Middle Pleistocene in age. The type species is T. antiqua. Several other species have been erected. Those named in the 19th century were distinguished primarily by the shape of their teeth, and have since been combined with T. antiqua. More recently erected species were reassigned from other tomistomine genera, although their assignment to Thecachampsa has since been questioned. The holotype of T. antiqua is an isolated tooth of little diagnostic value, making the assignment of any other body parts to the genus, including skulls and vertebrae, questionable.