Horsehead

Horsehead, also known by his Japanese name Mazura, is a horse-faced knight who acts as a boss in Zelda II: The Adventure of Link.

Zelda II: The Adventure of Link
In Zelda II: The Adventure of Link, Horsehead is the first boss, appearing in Parapa Palace. In the Japanese version, he additionally appears midway through the Palace on the Sea, though in western versions this is replaced with a blue Ironknuckle. Horsehead is taller than any of the previous enemies faced in the game, and his weak point is his unarmored head. As such, Link needs to jump to hit it. Horsehead walks slowly back and forth over a small area, and his only attack is to swing a morning star at medium height. The attack cannot be blocked by Link's shield and it does a relatively large amount of damage, so Link needs to jump away when he sees him start to swing. After being hit in the head enough times, Horsehead explodes.

The Legend of Zelda: Breath of the Wild
Horsehead does not directly appear in The Legend of Zelda: Breath of the Wild, although Orsedd Bridge is named after him. The bridge appears over a river where other nearby bridges have names based on the bosses from Zelda II: The Adventure of Link.

Captain N: The Game Master
In the Captain N: The Game Master episode Quest for the Potion of Power, Horsehead appears along with other elements from the game. Like most things on the show, he is off-model, in his case having a centaur-like body.

Trivia

 * Horsehead and Helmethead share the exact same leg graphics, just given a different palette.