Stalchild

Stalchilds, sometimes called Stalchildren, are recurring enemies in the Legend of Zelda series. They are undead skeletal-like creatures that seem to be closely related to Stalfos, except more child-like and unarmed.

In the original Japanese language versions of the games, Stalchilds are referred to as "Stalbabies" while the seemingly unrelated Skull Kid race are referred to as Stalchildren instead.

The Legend of Zelda: Ocarina of Time
Stalchilds relentlessly attack Link in Hyrule Field at night when he is a child. If Link wears the Bunny Hood, however, they will stop appearing. If he walks on the small paths scattered across Hyrule Field instead of on grassy areas, Stalchildren also do not appear. They are easy to take care of though, as they can be out run rather easily and dealt with very effectively by the use of a sword. However, if Link uses his sword, it will result in more Stalchilds appearing. If Link slays eleven ordinary Stalchilds in Hyrule Field, a larger Stalchild will appear. Despite its large size, it is not any stronger than a standard Stalchild. For every subsequent eleven Stalchildren Link defeats, an even larger Stalchild will appear. Although the night in Hyrule does not last long enough to show the full extent of this effect, a cheat device can be used to perpetuate the night. This can ultimately allow a Stalchild larger than Captain Keeta to appear.

The Legend of Zelda: Majora's Mask
In Termina, Stalchildren were once soldiers of the Ikana army led by Captain Keeta. They persevere to serve the Ikana Kingdom and its royal family, even beyond death. After defeating Captain Keeta and receiving the Captain's Hat, Link is able to speak to the Stalchilds while wearing the hat.

Link can order the Stalchilds found in Ikana Graveyard to open the graves for him. If he enters the grave they encircle on the First Day, he will eventually find a stone with the "Song of Storms" inscribed on it. Learning this song is crucial to advance in the game. On the other two nights, the graves will lead to a Piece of Heart and a bottle, respectively.

Stalchilds can also be found inside the Oceanside Spider House. Here, they give Link tips about the house and help him solve a puzzle that leads to a Piece of Heart.

Origins
It is possible that Stalchilds are Kokiri that have left the Woods, thus turning into Stalchilds. They could also be Hylians who are suffering the effects of the Lost Woods and that a Stalchild is an intermediary stage between Hylian and Stalfos. But since the supposed "fate" of those that get lost in the Woods says Stalfos, it seems unlikely, apart from the fact that Kokiri are seen outside the forest in one point at the end of Ocarina of Time, and whose law of "never leaving the forest or they will die", seems to be more of a warning of the outside world than their fates as children of the forest.