Joss Naylor, MBE is an English fell runner who set many long-distance records, and a sheep farmer, living in the English Lake District. As his achievements increased he became better known as the King of the Fells or simply the Iron Man.

Fell running, also sometimes known as hill running, is the sport of running and racing, off-road, over upland country where the gradient climbed is a significant component of the difficulty. The name arises from the origins of the English sport on the fells of northern Britain, especially those in the Lake District. It has elements of trail running, cross country and mountain running, but is also distinct from those disciplines.