Who was Emil Zatopek?

He invented the idea of interval training. The 'experts' laughed at him for training like a sprinter until he won the 5,000; the 10,000, and the marathon in a span of eight days at the 1952 olympics. And yes he set an olympic record in each one.
There is a short biography at this site :

http://www.runningpast.com/emil_zatopek.htm#1952_5k

as well as actual video footage of some of his races. If you have the bandwidth, it is well worth watching.