Astrapotherium ("lightning beast") is an extinct genus of large astrapotherian ungulate native to South America during the early-middle Miocene.

Other fossils have been found in the Deseado, Sarmiento, and Aisol Formations of Argentina and Chile (Cura-Mallín Group).

[2] Astrapotherium had an elongated body, with a total length around 2.5 m (8.2 ft), a weight of nearly 1,000 kg (2,200 lb), and relatively short limbs.

Its four canine teeth were elongated to form short tusks, and it had broad, protruding lower incisors, which likely ground against a horny pad in the upper jaw, as in many modern ruminants.

[5] Cladogram based in the phylogenetic analysis published by Vallejo-Pareja et al., 2015, showing the position of Astrapotherium:[6] Eoastrapostylops Trigonostylops Tetragonostylops Albertogaudrya Scaglia Astraponotus Maddenia Comahuetherium Parastrapotherium Astrapotherium Astrapothericulus Uruguaytherium Hilarcotherium Xenastrapotherium Granastrapotherium The animal was probably at least partially aquatic, living in shallow water in a similar manner to a modern hippopotamus.