The Yeonil O clan was one of the Korean clans. Their Bon-gwan was in Pohang, North Gyeongsang Province. According to the research in 1985, the number of Yeonil O clan was 1166. Their founder was . was a 7th descendant of who was a founder of Haeju Oh clan. was naturalized from Song dynasty during Seongjong of Goryeo’s reign in Goryeo.[1]