Here is "Ralphie," the University of Colorado's live mascot who runs at the beginning of each half at CU home football games. Watching it is pretty damned impressive.

You don't want to stand in Ralphie's way.
By the way, Ralphie is actually a female.
The Falcon, mascot of the United States Air Force Academy is said to be the only "performing" mascot in the NCAA.
The ones below also sometimes "fly by" during pregame at AFA. They're pretty damned impressive, too.