Laosaurus (meaning "stone or fossil lizard") is a genus of hypsilophodont dinosaur. The type species is Laosaurus celer, first described by O.C. Marsh in 1878 from remains from the Oxfordian-Tithonian-age Upper Jurassic Morrison Formation of Wyoming. The validity of this genus is doubtful because it is based on fragmentary fossils. A second species from the Morrison Formation, L. gracilis, and a species from the late Cretaceous of Alberta, Laosaurus minimus, are also considered dubious. It is believed that the three species were hypsilophodonts, basal ornithopods.

Laosaurus (meaning "stone or fossil lizard") is a genus of hypsilophodont dinosaur. The type species is Laosaurus celer, first described by O.C. Marsh in 1878 from remains from the Oxfordian-Tithonian-age Upper Jurassic Morrison Formation of Wyoming. The validity of this genus is doubtful because it is based on fragmentary fossils. A second species from the Morrison Formation, L. gracilis, and a species from the late Cretaceous of Alberta, Laosaurus minimus, are also considered dubious. It is believed that the three species were hypsilophodonts, basal ornithopods.