Rover

Rover, formerly known as Smasher, is a giant one-eyed stingray-like creature that fights by throwing a giant iron ball, which is also its only weakness.

The Legend of Zelda: Link's Awakening
In The Legend of Zelda: Link's Awakening, Rover is the main guardian of the Face Shrine, being found in one of the map's "eyes." It bounces around quickly, tossing the iron ball at Link even from all the way across the room, before quickly moving to retrieve it. If Link uses the Power Bracelet to pick up the ball, Rover bounces around panickedly to avoid being hit. If Rover is facing Link when he throws the ball, Rover may instead catch it. Damaging Rover four times defeats it. As with many other dungeon guardians, Rover has a respawning encounter in Turtle Rock.

The Legend of Zelda: Oracle of Ages
In The Legend of Zelda: Oracle of Ages, Smasher appears as the miniboss of the Crown Dungeon. He acts similar to before, though due to dungeon rooms in general being larger, there is more room for both Link and Smasher to avoid being hit. Smasher now turns red as it picks up the ball and again when it tosses it, though this does not affect anything. The ball itself vanishes randomly after a period of being out of Smasher's possession, even if Link is actively carrying it; it reappears elsewhere shortly after, and may do so closer to Smasher or Link or far from either. After five hits from the ball, Smasher is defeated.