Yu Sang
Yu Sang, alternatively Ryu Sang, courtesy name Yŏjin, was a royal court physician and politician of the Korean Joseon dynasty. He was a smallpox specialist who successfully treated three Joseon kings.
In 1693, due to having cured Sukjong's smallpox, he was granted a political office. Later he became the governor of Seosan, Goyang, Hapcheon and Saknyeong.
His experiences with smallpox are detailed in his book, Kogŭm Kyŏnghŏm Hwalyubang.
Supernatural anecdotes featuring him and a divine being circulated due to his fame.