The term 'Fast Runner' can be described by three different crossword solutions: HARE (4 letters), SPRINTER (8 letters), and EMU (3 letters). A HARE is a small mammal that is known for its speed and agility, and is found in many parts of the world. A SPRINTER is an athlete who specializes in running short distances at high speeds. Finally, an EMU is a large flightless bird native to Australia, and is capable of running at speeds of up to 30 miles per hour.