Gooma

Gooma is the boss of the Palace on the Sea in the American version of The Adventure of Link. In said version, it replaces Helmethead, who previously appears there for a rematch. He is a giant with a spike helmet that swings a spiked Ball and Chain at Link. Wearing no armor, his body is vulnerable, but not his head.

To defeat Gooma, Link must dodge the spiked ball that Gooma throws at him, then run up to Gooma, and hit him with his sword. It's advised to inmediately step back to avoid getting hit with the spiked weapon.

Trivia

 * This boss is not in the Japanese version, but the mole-like enemy holding a Ball and Chain (not named in the English version) is named Guma in the Japanese version. To differentiate between the enemies, fans in the Japanese community dub the western Gooma as the Jaianto (ジャイアント), roughly translating to "Giant", although this is not official.
 * Interestingly, there's another Nintendo character named Gooma; a Goomba from the game Mario whose species also has appeared in a Zelda game.