The Empty Child is a mob that attacks Villagers and converts them into Empty Villagers and Empty NPCs, similar to Minecraft Zombies and Cybermen. Appearing in only one story, it is one of few mobs to be based on a villain/monster from a single episode.
In The Show Edit
The Empty Child only appears in the two parted story 'The Empty Child/The Doctor Dances'. In the episode, the Doctor follows a mysterious object through the Time Vortex to 1941 London.
The Doctor discovers that the source of this plague is an alien ambulance, which saw the corpse of Jamie, who had been killed by a bomb, and resurrected him. Believing the Gas Mask to be part of him, it fused it to his body and had him convert any humans he came in contact with into this 'Empty' state.
In The Mod Edit
The mob has 20 health and converts Villagers to Empty Villagers upon the villager's death. All three variations will drop a gas mask and Rotten Flesh upon death. As of May 2014, the Empty child has the ability to edit signs to "Mummy? Are you my Mummy? Mummy?!", replicating his ability in the show.