Helmethead

Helmethead, also known by his Japanese name of Jermafenser, is the second boss of Zelda II: The Adventure of Link. He is a humanoid in a suit of armor with two separate helmets.

Zelda II: The Adventure of Link
In Zelda II: The Adventure of Link, Helmethead is the boss of Midoro Palace. In the Japanese version, he is also the boss of the Palace on the Sea, but in western versions this appearance is replaced with a new boss, Gooma. Despite having a sword, he does not use it to attack, instead spitting fireballs at Link. His armor can withstand sword beams. When hit in the head, his helmet pops off and falls behind him while another, crested helmet appears in its place. After the second helmet is removed, his real head emerges, showing he is a cyclops. The removed helmets fly through the air in a wavy pattern above the battlefield, and continue to shoot fireballs at Link. After being hit in the real head enough times, Helmethead explodes.

The Legend of Zelda: Breath of the Wild
In The Legend of Zelda: Breath of the Wild, Helmethead does not directly appear, though Helmhead Bridge is named after him. Other nearby bridges are named for other bosses from Zelda II: The Adventure of Link.

Captain N: The Game Master
In Captain N: The Game Master, Helmethead makes a cameo in Having a Ball, where he waves a fan at King Hippo.

Trivia

 * Helmethead and Horsehead have the same leg graphics, just colored differently.