Wallmaster
Wallmasters, also called Wall Masters, can be found in many Zelda Games but mainly Ocarina of Time. It hangs from the ceiling and creates a shadow around Link that grows and grows and grows until eventually, it drops and grabs Link and transports him back to the beginning of the dungeon. It makes an eerie sound which indicates that you should move and chop it to pieces when it lands and misses you, definatly one of the scariest enemies in the game.
NOTE:
1. To avoid confrontation entirely, switch to first person when the shadow appears and it should leave you alone (only tested in Oot).
2. When you see the shadow under you, simply run around, DO NOT STAND WHERE YOU ARE. Run around until it drops (behiind you) Then slash it with your sword. It'll be easier to keep slashing it until it dies, if you don't kill it then, it'll hind again and you'll have to waste time running.
3. If there's a ladder near by, quickly begin to climb it. The shadow may remain there, but your safe. Good luck figuring out how to get down... (same works for grassy walls)
Quote from The Legend of Zelda: The Minish Cap Wall Master figurine:
"Appears in dungeons. If these guys grab you, they'll send you back to the start of the dungeon. Dodge them as they fall, then attack."