Doomknocker

The Doomknocker is a soldier in blue armor, first encountered by Link in Island Palace in The Adventure of Link. They are similar in appearance to the Iron Knuckle, but they attack by throwing spiked clubs horizontally towards Link. These attacks cannot be blocked with Link's shield unless he uses the Reflect magic, so the best technique to destroy a Doomknocker is to use the Down Thrust technique after dodging their projectiles with jumps.

Non-Canon Appearances
A Doomknocker-like enemy appears in Captain N: The Game Master, during the episode entitled Quest for the Potion of Power. While searching for the Potion of Power, Kevin, Link, Princess Zelda and Game Boy reach the Island Palace and begin to explore. Coming across a huge door, Game Boy accidentally opens it without realizing that a huge and seemingly mechanical knight lay behind it. This giant bolt-covered guardian swings its club at Game Boy but misses, causing it instead to smash a nearby statue. Thinking fast, Kevin shoots the switch above the doorway to cause it to close before the Doomknocker can get past, trapping it behind the door.

Trivia

 * This enemy's Japanese name translates as "Hell Guma", a name shared with Guma, an enemy in the same game which has attacks and movement that are similar to the Doomknocker.