Bolosaurus (from Ancient Greek bolos, "lump" + sauros: lizard]) is an extinct genus of bolosaurid reptile from the Cisuralian epoch (middle Sakmarian to early Kungurian stages) of North Asia and North America (Red Beds of Texas and Oklahoma).

The skull is wider and higher in the posterior region, while the anterior snout terminates bluntly.

Teeth: Tooth planted in shallow cavity with its crowns expanded transversely to the jaw axis.

In the upper jaw, the posterior internal half of the maxillary series is low and horizontal, forming a ledge.

In 2024, a detailed anatomical study was published of Bolosaurus major which showed that this animal had a partial secondary palate, which may have allowed it to bite very hard.