Baron Iron Mask was a dictator who had been terrorizing the European continent. He was among the four members (along with General Sahara, Captain UFO, and Hell Boxer) of the Big Four lead by Iron Claw.
He fought Kamen Rider V3 in Europe off-screen. He led the Iron Mask Battalion, his own specialized troopers. He carried a heavy iron shield and battle spear which he can hurl with devastating skill and a blowgun which he can use to fire poison darts.
Facing the J.A.K.Q. and Goranger teams, Sahara and the rest of the big four combine into the super cyborg entity “Big Four Robo”, a monstrous and hulking mechanical monster with multiple cannons protruding throughout his body and a grinder in his lower torso. Virtually invincible, it took the combined special attacks of JAKQ's Big Bomber and Goranger's Goranger Hurricane Ball to destroy the monster.