The fastest animal on earth is, actually, the peregrine falcon, who can fly up to 200 mph! (mph is miles per hour, in case you didn't know) It is also endangered, so try to help this extraordinary bird!
People be warned don't listen to the retard above me. If all of the doo doo that is leaking out of his mouth was gently tossed out of a plane it could travel at a terminal velocity in the same vicinity of a diving falcon. A peregrine falcon can propel itself at around 55mph. Very fast, but not cheetah fast. Anyone who thinks that a peregrine falcon is the fastest animal is not very smart. The actually fastest animal is a bird called a swift which can PROPEL itself (not assisted by gravity) at around 100mph.