It's hard to say, but the most likely candidate would be 1973 Triple Crown winner Secretariat. The big chestnut colt set records in the Kentucky Derby and Belmont that may never be broken.
Secretariat was the fastest horse that ever lived
1:59.4 was he fastest and was a record set by Secretariat "The Greatest Horse That Ever Lived" at the Kentucky Derby.
The fastest person who ever lived is Usain bolt.
The fastest dinosaur that ever lived was the cheetah-sized dinosaur called the Compsognathus.
The cast of The Fastest Man Who Has Ever Lived - 2010 includes: Usain Bolt as himself
Alvin Lee
I think Phar Lap
UB is the fastest person ever timed for a 100m or 200m track race. is he the fastest human ever alive? We will never know.
Man o' War
The fastest dinosaur that ever lived was the cheetah-like dinosaur called the Dromiceiomimus, which could run up to speeds of 60 miles per hour.
Twister type him in on youtube/google
Fritz the Horse went by The Greatest All-Round Horse That Ever Lived.