Yeonsangun of Joseon, born Yi Yung on November 23, 1476, was the tenth ruler of the Joseon dynasty in Korea, reigning from 1494 to 1506. His rule is often considered the most tyrannical in Korean history. Initially, Yeonsangun believed he was the son of Queen Jeonghyeon. After ascending to the throne in 1494, he began his reign effectively, focusing on national defense and aiding the poor. However, his violent tendencies surfaced early when he killed one of his tutors.

The turning point in his reign came when Yeonsangun discovered the truth about his biological mother. His efforts to posthumously restore her titles were opposed by government officials, leading to his growing resentment towards them. This resulted in the First Literati Purge in 1498, where many officials of the Sarim faction were executed following an accusation of treason against Gim Il-son and his followers.

In 1504, the Second Literati Purge occurred after Yeonsangun learned about his mother's death in detail. He brutally killed those he believed responsible, including royal concubines and officials, and desecrated the grave of Han Myeong-hoe. Yeonsangun's punishments extended to anyone present in the court during his mother's mistreatment.

Yeonsangun's rule further deteriorated as he converted educational and religious institutions into personal pleasure grounds, forcibly gathered young girls for entertainment, and evicted thousands to build hunting grounds. His actions led to widespread mockery and opposition. In response, he banned the use of Hangul and attempted to dismantle Buddhism in Joseon. His oppressive policies extended to court officials, leading to the abolition of critical government offices. His brutal treatment of dissenters, including Chief Eunuch Gim Cheo-sun, further showcased his tyranny.

In September 1506, a coup led by a group of officials overthrew Yeonsangun, replacing him with his half-brother, Grand Prince Jinseong. Yeonsangun was demoted to Prince Yeonsan and exiled to Ganghwa Island, where he died two months later. His concubine Jang Nok-su, who had supported his misrule, was executed, and his young sons were forced to commit suicide. Yeonsangun's reign is remembered as a stark contrast to the more liberal era of his father and as a period of extreme despotism in Korean history.