Guru Pathik was the minor character of Avatar: The Last Airbender. He was a nomadic supercentenarian who possessed great knowledge of the Spirit World and its effects on normal humans, as well as the nature of the Avatar and the Avatar State. He was spiritually enlightened and had assisted numerous people, as well as animals like Appa, attain their full potential and cleanse themselves of pain and suffering. Pathik was willing to teach everybody who wished to learn from him, and his nationality was unclear, as he did not seem to hold an allegiance to any one nation and preferred to operate outside of borders.
One of the oldest people in the Avatar world, Pathik has been alive long enough to have known the Air Nomads. Seeking out the Eastern Air Temple after a vision, he patiently waited for the Avatar there. He encountered Appa while the sky bison had been separated from Aang, and used a special technique to locate the Avatar. He also attached a note to Appa's horn, promising that he could teach Aang to master the Avatar State. When Aang came looking to take him up on his offer, he instructed the young Avatar on how to unlock his chakras, pools of energy in the body that must be opened for the Avatar State to function properly. Aang was able to open all but the last one, because the process involved letting go of Katara.
Pathik's spirituality and connection with the natural world allow him get along greatly with animals, even allowing him to help heal Appa's rage and fear in "Appa's Lost Days". Like Gyatso, his good friend, he is an affable and wise old man.