Aang

Avatar Aang, an Air Nomad, was the Avatar during the century-long conflict known as The War. His immediate predecessor was Avatar Roku, and his immediate successor was Avatar Korra. Being the manifestation of the world in human form, Aang was the only person in the Avatar world who could use all four bending disciplines: Airbending, Waterbending, Earthbending and Firebending. He is the main protagonist in Avatar: the Last Airbender. He is also one of a select few Avatars, and one of the first in many years, to learn the ancient art of Energybending, and the only Avatar to use it during the series