Shy Guy

Mask-Mimics are easy to defeat (although annoying) creatures found in Link's Awakening. They copy all of your movements, but go in the opposite direction, (for example, if you move to the right, they go left) and cannot be hurt from the front due to their masks. The easiest way to defeat them is to trick them into exposing their back, and do a Spin Attack.

Trivia
Link's Awakening was full of Mario cameos/references, and the Mask-Mimic is just another one of them, as they resemble Shy Guys from Super Mario Bros. 2