Lanmolas

The three Lanmolas guard the Pendant of Power in the second dungeon of A Link to the Past. They dig out of the floor somewhere in the room, then fly a while and dive back into the sand. In this time they can be hit on the head or tail with Ice Rod or Sword. After they are defeated, Link gets the Pendant of Power and a Heart Container.

Later in Ganon's Tower they guard the way up.

One did appear Link's Awakening as a mini-boss. It's guarded the Angler Key.