Grim Creeper

The Grim Creeper is a mini-boss and character in the game. He appears to be a humanoid with a skull for head, and a fondness for bats. Link encounters him midway through the Eagle's Tower dungeon of. After a short introduction, Grim Creeper proceeds to use a flute to call six Battle Bats to attack Link. To defeat them, Link must destroy the Keese before they leave the screen. If he misses any, he has to try again. Any weapon will do, but the sword is by far the easiest to use. Once all the Battle Bats are destroyed in one blow, Grim Creeper flees, but not before vowing revenge for his beloved bats. He lives up to his word in the final boss battle in Eagle's Tower, where he sends away his remaining bats, and uses his flute to summons Evil Eagle as a mount. Upon the defeat of the Creeper, and Evil Eagle, he uses his last breath to warn that all, Link included, will be lost if the Wind Fish's wakes, as they're all in his dream.

Link's Adventure Manga
In the, the Grim Creeper, and Evil Eagle appear in chapter 7. Earlier Moblins had captured Felicia, and given her to Creeper. The Grim Creeper attempts to dissuade Link from attacking by pointing out Felicia as a hostage, but Link manages to cut through only the Creeper, and Evil Eagle.

Trivia

 * The flute the Grim Creeper uses may be a reference to the Flute from the original . Judging by the creature's Japanese name, it is a piccolo.
 * The Skull Kids may have been inspired by the Grim Creeper, as they also play a flute that they use as a weapon or to summon monsters and also wear Skull Masks. Whether Grim Creeper is wearing a mask or not is unclear.
 * The battle with the Twilit Carrier Kargarok is similar to the battle with Evil Eagle and Grim Creeper, as both involve a masked rider commandeering a huge bird.

Etymology
The Grim Creeper's name is an obvious reference to the Grim Reaper.