Greg Powell is a stuntmant and stunt coordinator who worked as the horsemaster on the 1988 fantasy movie Willow. In addition to teaching Patrick Roach how to ride, Powell also doubled for him in certain scenes.
During the shooting of one scene in which Airk Thaughbaer (Gavan O'Herlihy) talks with Madmartigan (Val Kilmer) from atop his steed, the horse became frisky, and the cameraman could not keep him in shot during close-ups. The director then decided to sit O'Herlihy on the shoulders of Greg Powell, who shuffled himself about to give the impression that O'Herlihy was on a horse.
Powell also played the Nockmaar soldier who tells Madmartigan to "keep [his] mouth shut!" and hits him, knocking him off his horse.