Gooma

Gooma was the boss of the 5th palace in the American version of Zelda II: The Adventure of Link, replacing Helmethead, who previously appeared there for a rematch. He was a giant with a spike helmet that swung a spiked ball & chain at Link. Wearing no armor, his body was vulnerable, but not his head.

To defeat Gooma, Link should dodge the spiked ball that Gooma throws at him, and then run up to Gooma, and hit him with his sword. Immediately step back to avoid getting hit with the spiked ball again.

Trivia
This boss was not in the Japanese version, but the mole-like ball 'n chain throwing enemy 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 International 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.