Seymouria is an extinct genus of seymouriamorph from the Early Permian of North America and Europe. Although they were amphibians, Seymouria were well-adapted to life on land, with many reptilian features—so many, in fact, that Seymouria was first thought to be a primitive reptile. It is primarily known from two species, Seymouria baylorensis and Seymouria sanjuanensis. The type species, S. baylorensis, is more robust and specialized, though its fossils have only been found in Texas. On the other hand, Seymouria sanjuanensis is more abundant and widespread. This smaller species is known from multiple well-preserved fossils, including a block of six skeletons found in the Cutler Formation of New Mexico, and a pair of fully grown skeletons from the Tambach Formation of Germany, which were fossilized lying next to each other.

Seymouriamorpha were a small but widespread group of limbed vertebrates (tetrapods). They have long been considered stem-amniotes (reptiliomorphs), and most paleontologists still accept this point of view, but some analyses suggest that seymouriamorphs are stem-tetrapods. Many seymouriamorphs were terrestrial or semi-aquatic. However, aquatic larvae bearing external gills and grooves from the lateral line system have been found, making them unquestionably amphibians. Though as they matured, they became more terrestrial and reptile-like. They ranged from 30 cm long lizard-sized creatures to the 1.5 m long Enosuchus. If seymouriamorphs are reptiliomorphs, they were the distant relatives of amniotes. Seymouriamorphs form into three main groups, Kotlassiidae, Discosauriscidae, and Seymouriidae, a group that includes the best known genus, Seymouria. The last seymouriamorph became extinct by the end of the Permian.