John Yi Yun-il was a 19th-century Korean farmer and catechist who served as a teacher of the Christian faith. Born in Korea, he lived during a period of intense religious suppression. He was executed in Daegu in 1867 following the Catholic Persecution of 1866. During his death at a military training center, he endured severe flogging before being decapitated. He is recognized as a saint in the Catholic Church for his steadfastness during these persecutions.