Rinconsaurus is a genus of titanosaur sauropod dinosaur from the Late Cretaceous in what is now Argentina. The type species, Rinconsaurus caudamirus, was described by Calvo and Riga in 2003, and is based on three partial skeletons.

Titanosaurs were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still thriving at the time of the extinction event at the end of the Cretaceous. This group includes some of the largest land animals known to have ever existed, such as Patagotitan—estimated at 37 m (121 ft) long with a weight of 69 tonnes —and the comparably-sized Argentinosaurus and Puertasaurus from the same region.