The Pantherinae is a subfamily of the Felidae; it was named and first described by Reginald Innes Pocock in 1917 as only including the Panthera species. The Pantherinae genetically diverged from a common ancestor between 9.32 to 4.47 million years ago and 10.67 to 3.76 million years ago.

Panthera atrox, better known as the American lion, also called the North American lion, or American cave lion, is an extinct pantherine cat. Panthera atrox lived in North America during the Pleistocene epoch, from around 340,000 to 12,800 years ago. The species was initially described by American paleontologist Joseph Leidy in 1853 based on a fragmentary mandible (jawbone) from Mississippi; the species name ('atrox') means "savage" or "cruel". The status of the species is debated, with some mammalogists and paleontologists considering it a distinct species or a subspecies of Panthera leo, which contains living lions. However, novel genetic evidence has shown that it is instead a distinct species derived from the Eurasian cave or steppe lion, evolving after its geographic isolation in North America. Its fossils have been excavated from Alaska to Mexico. It was about 25% larger than the modern lion, making it one of the largest known felids.