Terrifying Masked Hero

"Goliath" (Steve Reeves) in GOLIATH & THE BARBARIANS was meant to be a terrifying nemesis played by the story's hero, not villain. There were a couple of films with the same idea.

The Red Wolf in REVOLT OF THE PRAETORIANS was basically the same thing as GOLIATH & THE BARBARIANS. Richard Harrison played the masked nemesis/hero.

A faceless hero in THE TERROR OF THE RED MASK.

Ed Fury plays an anti-hero in THE SEVEN REVENGES; at one point in the film he starts wearing a mask to conceal his face while he tries to crush his opponent.

A faceless rebel leader jeopardizes the plans of the ten gladiators in TRIUMPH OF THE TEN GLADIATORS; previously we saw the rebel leader destroy some valuable property (a scene lifted from COLOSSUS OF RHODES)