Achaenodon is an extinct artiodactyl mammal, possibly belonging to the family Helohyidae.

It lived in the mid-late Eocene (about 43-39 million years ago) and its fossil remains have been found in North America.

[1] Achaenodon was around the size of a pig[2] or a black bear,[3] with a body mass of around 200–285 kilograms (441–628 lb).

[3] First described in 1873 by Edward Drinker Cope, Achaenodon is best known for fossil remains from the Wyoming Middle Eocene.

[5] Some studies have suggested that Achaenodon could be a basal representative of Cetancodontamorpha, and closely related to entelodonts.