Lao Ge

Lao Ge, also known as Tieguai, was a nomadic assassin who possessed great spiritual knowledge and had unlocked the secret to immortality. Under the cover of an old criminal and drunkard, Lao Ge travelled around the world and killed those whom he regarded as wrongdoers who worsened the suffering of many people. Over time, he took many disciples, one of them Avatar Kyoshi, whom he taught about assassination and spirituality.

History
The origin, birth name, and age of Lao Ge was unknown. According to legends in the Earth Kingdom's underworld, he was at least two hundred years old. If one of his comments was true, and not meant as joke, he was personally acquainted with Guru Shoken. In this case, he would have been over four thousand years old, and been born before the four nations were unified. He had several disciples during his life, most of whom were only interested in learning about the secret of immortality from him. At some point, he adapted the name "Tieguai", and became infamous in the Earth Kingdom for murdering the 40th Earth King. Adopting the name "Lao Ge". he eventually joined the Flying Opera Company, a daofei outlaw group led by Hark and Jesa, using the outfit as cover for his assassinations. Unbeknownst to him, Jesa figured out who he was, and wrote it down in a journal which she passed to her daughter, Avatar Kyoshi.