Elemgasem (after a Tehuelche god of the same name) is an extinct genus of brachyrostran abelisaurid from the Late Cretaceous Portezuelo Formation of Patagonia, Argentina.

[1] The Elemgasem holotype specimen, MCF-PVPH-380, was discovered in 2002 in layers of the Sierra del Portezuelo locality of the Portezuelo Formation, about 20 kilometres (12 mi) west of Cutral Có, Neuquén Province, Argentina.

The generic name, "Elemgasem", references a Tehuelche deity of the same name; according to mythology, Elemgasem is the owner of animals and father of the southern viscacha with the power to petrify others and himself, as well as the inhabitant of the mountains and sky.

Named taxa recovered from the formation include the theropod dinosaurs Megaraptor, Patagonykus, Neuquenraptor, Pamparaptor, and Unenlagia, the sauropod dinosaurs Futalognkosaurus, Malarguesaurus, and Baalsaurus, and the azhdarchoid pterosaur Argentinadraco.

Other fossils belonging to ornithopod dinosaurs, neornithines, turtles, and crocodiles have also been found in the formation.