And you thought they were just imaginary creatures from Game of Thrones - like dragons or naked ladies. Nope! They were real. And freaking SCARY. Or at least Wikipedia says they were real. And Wikipedia always tells the truth.
According to the repository of all human knowledge, they were up to 1.2m long, and weighed as much as 109kg. Because good ole canis lupus isn't scary enough maxing out at 38kg. But don't worry, dire wolves went out of business about 10,000 years ago, apparently because they were too slow to catch quick prey. That, at least, is something to consider during the nightmare you're going to have tonight: Run fast if you want to survive. [Wikipedia via @Blam]