Peter Snell (New Zealand) 3

Snell was not a distance runner, per se, because his longest competitive distance was the mile.  He's a middle distance runner, and one of the best of all time, holding three world's records at one time or another.  But, looking over this list, where's Emil Zatopek?  After all, he is the only man ever to win Gold Medals in the 5,000m, 10,000m and marathon in the same Olympics.