Lesothosaurus is a part of the herbivorous clade of dinosaurs, the Ornithischia. It was named by paleontologist Peter M. Galton in 1978, the name denotation "lizard from Lesotho".

Lesothosaurus was originally measured an ornithopod. However, more recent work by Paul Sereno has optional that it may actually represent one of the primitive of all known ornithischian dinosaurs. The taxonomic history of Lesothosaurus is multifaceted, and it has long been puzzled with Fabrosaurus, another small ornithischian from the same locality.

Lesothosaurus was a small (one meter in length), bipedal plant-eater. It lived in the hot, arid circumstances of Lesotho and South Africa during the Early Jurassic. Remains of Lesothosaurus have been composed from the Upper Elliot Formation.