Energybending

History
Aang uses spirit bending in the Avatar series' finale "Sozin's Comet." Throught the advice from the giant lion-turtle Aang previously mistaken for a island. Spirit bending has the ability to take away someones bending as seen in Avatar Aang forever. Which in the Avatar world, can be a fate worse than death, ecspecially for former Fire Lord Ozai, whom used to torment and destroy life with his powers.

Benders
So far, only Aang whilst in the controlled Avatar State, is able to use this ability. Though since it is a very old technique, it can be presumed that only the first few Avatars would know of this technique. Also, it can be assumed that one would need to be in the Avatar State whilst in complete control in order to be able to know of the existence of this ability and how to use it.