The Scimitar-Toothed Cat. And the subject of one of the most incredible recent Ice Age discoveries with the mummified cub from last year.
This was an astonishingly successful predator of the Pleistocene, found on nearly every continent in the world during the epoch. It also specialized in hunting hominids, and most of our recognized ancestors from Homo habilis to the Neanderthals encountered them.
It survived from the early Pliocene all the way to the end of the Ice Age, dying out with most of the other megafauna.