Mazura

Horsehead is the first boss in The Adventure of Link, and is encountered in the penultimate chamber of the Parapa Palace, protecting the temple's statue. Upon his defeat, like all bosses in the game, a key drops from above that allows Link to pass through into the final room that contains the Stone Statue to set the Crystal into.

Strategy
Horsehead wields a mighty, spiked club and sports heavy armor around its entire body, except for the head. In this battle, Link must perform continuous jump slashes with his sword at the boss' weak skull; it is the only way to inflict damage. The boss' club is the most detrimental weapon Link encounters in the game thus far - in only a few blows, Link's health may be completely depleted. As such, Link is knocked back significantly harder and further when struck by Horsehead's club, compared to distance Link is pushed away by other enemies' attacks. Horsehead also attempts to slowly herd Link towards one side of the screen, giving Link little opportunity to escape while the boss bludgeons him with persistent blows. After a significant amount of hits, Horsehead explodes and Link is provided 50 experience points.

Although it is not necessary to battle Horsehead with anything other than the sword, use of the Shield magic will greatly reduce the damage dealt by Horsehead's blows.

Captain N: The Game Master
Horsehead appears in the "Quest for the Potion of Power" episode of Captain N: The Game Master. He appears after Link takes the Golden Key in the Parapa Palace, revealing himself to be the guardian of the key. Link decides to fight Horsehead alone, but he is easily bested by the monster and loses his sword after one of the monster's attacks, leaving the young hero defenseless. Just as Horsehead is about to deliver a deadly blow to Link, Kevin rescues Link and defeats Horsehead instead by remembering his weakness: his head. Knowing so, Kevin shoots at the ceiling using his Zapper, causing the ceiling to collapse on top of Horsehead and thus dispose of the foe.

Trivia

 * In the Japanese version of the game, Horsehead roars during battle, similar to the bosses from The Legend of Zelda.
 * Horsehead also appears twice in the Japanese version; a second Horsehead is in the Palace on the Sea, prior to a false wall. Defeating him gives Link a key, much like fighting him in Parapa Palace. In the NES version, he was replaced with a Blue Iron Knuckle, and the locked door after the false wall was removed.
 * Horsehead was referred to by his Japanese name, Mazura, in The Official Nintendo Player's Guide section covering Zelda II.