Fabrosaurus (/ˌfæbrəˈsɔːrəs/[1] FAB-rə-SOR-əs) is a dubious extinct genus of ornithischian dinosaur that lived during the Early Jurassic during the Hettangian to Sinemurian stages 199 - 189 mya.

[2] It was originally placed within the now obsolete family Fabrosauridae (now considered basal Ornithischia).

[2] Fabrosaurus was named and described by paleontologist Leonard Ginsburg in 1964 based on the holotype specimen, MNHN LES9, a partial jawbone with three teeth.

[4][5] However, as additional ornithischian fossils were discovered, the features of F. australis were thought to be shared by other species, and by the 1990s and 2000s most authors working with the group found Fabrosaurus to be a nomen dubium (doubtful name), finding the holotype material described by Ginsburg to be insufficient to distinguish a new taxon.

Some claim the fossils represent simple variation of Lesothosaurus, which is regarded as a valid taxon.