Hesperocyon is an extinct genus of canids (subfamily Hesperocyoninae, family Canidae) that was endemic to North America, ranging from southern Canada to Colorado.

Hesperocyon was assigned to Borophagini by Wang et al. in 1999[2] and was the earliest of the canids to evolve after the Caniformia-Feliformia split some 42 million years ago.

[3] The Canidae subfamily Hesperocyoninae probably arose out of Hesperocyon to become the first of the three great dogs groups: Hesperocyoninae (~40–30 Ma), Borophaginae (~36–2 Ma), and the Caninae lineage that led to the present-day canids (including grey wolves, foxes, coyotes, jackals and dogs).

Unlike modern canids, Hesperocyon had five fingers and toes and a dew claw deeply set enough to suggest tree climbing capabilities.

The youngest fossil was recovered from the Dog Jaw Butte site, Goshen County, Wyoming dating to the Arikareean age (NALMA) of the Oligocene and Miocene 42.5 mya—31.0 Ma.