well for starters in the Pleistocene era you had the Thylacoleo carnifex and prissidens, that would be fairly unpleasent to run into in the middle of the night, there was the Megalania prisca and Quinkana not mamalian but unpleasen none the least, there was a giant killer kangaroo who's name I can't remember (or find, but I remember reading about it a few years ago though), Sarcophilus laniaris, other non preditory animals that would probly rather kill you than look at you.
many of these went extinct less than 20,000 years ago, durring the last ice age, when many other animals around the world got it