A cheetah! When running, because most of the time they are in the air and their paws only touch the ground for a short amount of time, it seems like they are almost flying. Here's more information on cheetahs from a blog post that Jamie did. http://jamiejason.blogspot.com/2014/04/cheetahs.html
Clue #1 They are in the feline family
Clue #2 When running, they spend most of the time up in the air, not touching the ground.
Clue #3 They can run up to 70 miles per hour! They are the world's fastest land mammal.