Jermafenser

Helmethead is the second boss of Midoro Palace in The Adventure of Link.

Strategy
His weak point is his head, and he attacks Link by throwing fireballs at him from his head. When Link lands a blow to his head, the helmet will come off and be replaced by another one. The detached helmet will then begin to float around and attempt to kill Link by shooting more fireballs and running into him. When Link knocks off two helmets, his true head will rise from the armor; a white head (seemingly with one eye). For the rest of the battle, Link fights the boss while also dodging the fireballs shot by the helmets. After achieving victory in the fight, Link returns one of the Crystals to the palace.

Famicom Disc System
In the Japanese version, Helmethead appears twice, first in Midoro Palace, where he is weaker than his NES counterpart due to only having one floating helmet, and a second time as the boss of the Palace on the Sea, where he is stronger and also has two helmets like the NES version. In the NES version, Gooma replaces the second Helmethead as the fifth boss.

Trivia

 * The Official Nintendo Player's Guide referred to Helmethead as "Jermafenser", a translation of his Japanese name.