Anoplosaurus (meaning "unarmored or unarmed lizard") is an extinct genus of nodosaurid dinosaur, from the late Albian-age Lower Cretaceous Cambridge Greensand of Cambridgeshire, England. It has been classified with the armored dinosaurs and ornithopods, but current thought has been in agreement with the "armored dinosaur" interpretation.
Harry Govier Seeley named this genus in 1879 for a partial postcranial skeleton, composed of dentary fragments, numerous vertebra from the neck, back, and sacrum, parts of the pectoral girdle, humerus fragments, part of the left femur, left tibia, foot bones, ribs, and other fragments. He regarded it as possibly juvenile, due to its small size. Other workers began to see it as an armored dinosaur, until 1923 when Franz Nopcsa suggested that some of the remains belonged to a camptosaur, and other remains, which he removed from the genus, belonged to Acanthopholis. This suggestion was followed (with modifications as iguanodontian taxonomy changed over the years), Suberbiola and Barrett reexamined the material. They wrote that the material all belonged to a primitive nodosaurid, the lack of armor possibly due to the young age of the animal at death. Reviews since then have followed this interpretation of the genus as an armored dinosaur.
A second species, A. major, was named by Seeley in 1879 for a neck vertebra and three partial caudal vertebrae he removed from Acanthopholis stereocercus, from the same formation as the type species. This species now appears to be chimeric, the neck vertebra coming from an ankylosaur, the caudals from an indeterminate iguanodont.