Gooma

Gooma (ジャイアント, Giant) 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 morning star 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' Japanese name is Jaianto, roughly translating to "Giant", whereas the mole-like ball 'n chain throwing enemy is the one named Guma, which translates into Gooma. A possible translation mixup?

Interestingly, there's another Nintendo character named Gooma; a Goomba from the game Mario whose species also has appeared in a Zelda game.