Algoasaurus (/ælˌɡoʊ.əˈsɔrəs/; "Algoa Bay reptile") is a genus of sauropod dinosaur from the Tithonian-early Valanginian-age Late Jurassic-Early Cretaceous Upper Kirkwood Formation of Cape Province, South Africa. It was a neosauropod; although it has often been assigned to the Titanosauridae, there is no evidence for this, and recent reviews have considered it to be an indeterminate sauropod.
The type species, A. bauri, was named by Robert Broom in 1904 from a back vertebra, femur and an ungual phalanx. The fossils were recovered in 1903 from a quarry by workmen who did not recognize them as dinosaur specimens, so many of the bones were made into bricks and thus destroyed. The animal may have been around 9 m (30 ft) long when it died.