Chasmaporthetes, also known as Hunting or Running Hyena, is an extinct genus of hyena endemic to North America, Africa, and Asia during the Pliocene-Pleistocene epochs, living from 4.9 mya—780,000 years ago, existing for approximately 4.12 million years. The genus probably arose from Eurasian Miocene hyenas such as Thalassictis or Lycyaena, with C. borissiaki being the oldest known representative. The species C. ossifragus was the only hyena to cross the Bering land bridge into the Americas, and ranged over what is now Arizona and Mexico during Blancan and early Irvingtonian Land Mammal Ages, between 5 to 1.5 million years ago.
Chasmaporthetes was one of the so called "dog-like" hyenas (of which the aardwolf is the only survivor), a hyaenid group which, in contrast to the now more common "bone-crushing" hyenas, evolved into slender limbed cursorial hunters like modern canids.
The genus has entered the popular culture lexicon as a result of cryptozoologic claims, having been proposed as the likely origin of the American Shunka Warakin and the Cuitlamiztli.