A Baneling is an agent of the Keeper. They are followers of the Keeper, doing his bidding. They often do very evil things, including beating people to death, falsely accusing other, innocent people as being banelings themselves, and so much more.
Zedd mentioned in Stone of Tears that banelings are known by many names. Darken Rahl himself mentioned that he was an agent, meaning that he himself was also a baneling. The Sisters of the Dark are also banelings.
- In the Legend of the Seeker television series, banelings are those that have died and been offered a second chance of life in service to the Keeper. They are required to kill a person a day in order to stay in the world of the living. The clock is reset after each kill. Therefore killing multiple people at once will not result in multiple days of life for the baneling. In the television series, Darken Rahl and the Sisters of the Dark do not count as banelings, in this sense, although in the episode "Extinction" we learn by Darken Rahl himself that he was a baneling (the very first one) before he was killed by Richard Cypher.
- The only way to prevent banelings from returning is by destroying their physical bodies, e.g. by burning them, while their souls are trapped in the Underworld.