A saber-toothed cat (alternatively spelled sabre-toothed cat) is any member of various extinct groups of predatory mammals that were characterized by long, curved saber-shaped canine teeth. The large maxillary canine teeth extended from the mouth even when it was closed. The saber-toothed cats were found worldwide from the Eocene epoch to the end of the Pleistocene epoch (42 million years ago (mya) – 11,000 years ago), existing for about 42 million years. The first saber-toothed cat fossil in Canada was found in Medicine Hat, Alberta.
One of the best-known genera is Smilodon, species of which, especially S. fatalis, are popularly, but incorrectly referred as a "saber-toothed tiger," a genus within the subfamily Machairodontinae of the carnivoran family Felidae. Extant members of Felidae include cats of the subfamilies Felidae and Pantherinae.