Oxyaenidae ("sharp hyenas") is a family of extinct carnivorous placental mammals. Traditionally classified in order Creodonta, this group is now classified in its own order Oxyaenodonta ("sharp tooth hyenas") within clade Pan-Carnivora in mirorder Ferae. The group contains four subfamilies comprising fourteen genera. Oxyaenids first appeared during the late Paleocene in North America, with smaller radiations of oxyaenids in Eurasia occurring during the Eocene.

The name of order Oxyaenodonta comes from Ancient Greek ὀξύς (oxús) 'sharp', name of hyena genus Hyaena and from Ancient Greek ὀδούς (odoús) 'tooth'.

The name of family Oxyaenidae comes from Ancient Greek ὀξύς (oxús) 'sharp', name of hyena genus Hyaena and taxonomic suffix "-idae".

They were superficially cat-like mammals that walked on flat feet, in contrast to modern cats, which walk and run on their toes. The largest known oxyaenid was Sarkastodon mongoliensis, which could’ve weighed 800 kg (1,800 lb). However, this may have been an overestimate. While many oxyaenids, such as Patriofelis, were carnivores, some such as Oxyaena, were omnivorous.

Many oxyaenids like Patriofelis, were adapted for terrestrial locomotion, however macheroidines were adapted for either scansorial or arboreal locomotion, based on their forelimb morphology.

Oxyaenodonts were believed to have evolved in the middle Paleocene in North America with the oldest known oxyaenodont, Tytthaena, being found there. Oxyaenodonts would disperse into Europe near the Paleocene-Eocene boundary via the De Geer route, however the timing of arrival in Asia is unknown.

Cladogram according to Gunnel in 1991: