The extinct American Lion (Panthera leo atrox) was one of the biggest cats to ever live. Larger than the even the huge Siberian tigers of Asia, It had possibly the largest brains of any cat alive or extinct. The head-body length of the American lion was around 8 feet long. It stood 4 feet at the shoulder and has been estimated to weigh in around 930 lb. The features and teeth of the extinct American lion strongly resemble modern lions, but they were considerably larger. These animals became extinct about 11,000 years ago.

The earliest lions known in the Americas south of Alaska are from the Sangamonian Stage (the last interglacial). After that, the American lion spread widely from Alberta to Maryland to Peru. In North America, it has been found in more locations in the west than in the east and as far south as Chiapas, Mexico.