Reapling
Reaplings appear in Phantom Hourglass, when Link makes his way on to the Ghost Ship. Reaplings, unlike Phantoms, deal two hearts of damage to Link and do not knock him unconscious.
Reaplings can be avoided by only moving when they have their backs turned to Link. Unlike Phantoms, Reaplings can move and see through walls. They are immune to most forms of attack and cannot be killed, but a shot to the back with an arrow will temporarily stun them. They can also be stunned if hit in the back with Oshus's Sword infused with Leaf, the Spirit of Power. They may be modified phantoms. They may also be former adventurers or victims of the ghost ship, suggested by the first cubus sisters line;
They seem to be subservient to the Cubus Sisters, since the Sisters initially tried to leave the task of dispatching Link to them, and were later disappointed when they failed.