Bulbasaurus (meaning "bulbous reptile") is an extinct genus of dicynodont that is known from the Lopingian epoch of the Late Permian period of what is now South Africa, containing the type and only species B. phylloxyron. It was formerly considered as belonging to Tropidostoma; however, due to numerous differences from Tropidostoma in terms of skull morphology and size, it has been reclassified the earliest known member of the family Geikiidae, and the only member of the group known from the Tropidostoma Assemblage Zone. Within the Geikiidae, it has been placed close to Aulacocephalodon, although a more basal position is not implausible.

Bulbasaurus was ostensibly not directly named after the Pokémon Bulbasaur, but rather after its nasal bosses, which are unusually bulbous among geikiids; however, the describers noted that the similarity in name "may not be entirely coincidental." Additionally, the specific name of the type species means "leaf razor", which is most directly a reference to its keratin-covered jaws. Other distinguishing characteristics of Bulbasaurus among the geikiids include the hook-like beak, very large tusks, and absence of bossing on the prefrontal bone.

Bulbasaurus was described by Christian Kammerer and Smith in 2017. The description states that the generic name combines the Latin bulbus, referring to the very large and bulbous nasal bosses, with the common suffix -saurus. As for the specific name phylloxyron, meaning literally "leaf razor", it is derived from the Greek phyllos and xyron, and apparently refers to the keratinous covering on the premaxilla, maxilla, and palate that would have been used to shear plant material. Thus, as published, the name of Bulbasaurus does not directly refer to Pokémon, or specifically the similarly-named Bulbasaur. However, Kammerer noted that "if one wished to read between the lines concerning certain similarities, I wouldn't stop them", and later added that "similarities between this species and certain other squat, tusked quadrupeds may not be entirely coincidental."