King Heonjong, previously known as Prince Moon-eung (Hanja: 憲宗王 [文應君]; Born: 8 September 1827 – Died: 25 July 1849), born Yi Hwan (이환/李奐) was the 24th king of the Joseon Dynasty. He was the grandson of King Sunjo. His father was Crown Prince Hyomyeong (posthumously named as Emperor Munjo-Ikjong, Emperor Ik of Korean Empire), who died at the age of 21 before becoming king and his mother was Queen Sinjeong of the Pungyang Jo clan. Heonjong was born three years before Hyomyeong's death.
Heonjong ascended to the throne in 1834 at the age of 8 after his grandfather, King Sunjo, died. Like King Sunjo, Heonjong took the throne at a young age and his grandmother, Queen Sunwon served as regent. Although King Heonjong ascended to the throne, he had no political control over Joseon. When Heonjong reached adulthood, Queen Sunwon refused to give up control. In 1840, the control over the kingdom was then handed down to the Andong Kims, the family of his grandmother Queen Sunwon, following the anti-Catholic Gihae Persecution of 1839.
King Heonjong died after reigning for 15 years in 1849 at the young age of 21. He was buried at the Royal Tomb of Gyeongneung within the Donggureung Tomb Cluster in 197 Donggureung Avenue/Donggureungno, Inchang-dong san 9-2 beonji, Guri City, Gyeonggi Province, where several kings and queens of the Joseon Dynasty was buried. As King Heonjong died without an heir, the throne passed to a distant descendant of King Yeongjo, King Cheoljong.
As was customary with the Annals of the Joseon Dynasty, the chronicle of Heonjong's reign was compiled after his death, in 1851. The compilation of the 16-volume chronicle was supervised by Jo In-yeong. King Heonjong is the last king to be buried at the Royal Tomb Cluster of Donggureung.
He was posthumously known as King Heonjong Gyeongmun Wimu Myeong-in Cheolhyo the Great (헌종경문위무명인철효대왕/憲宗經文緯武明仁哲孝大王). In 1897, Emperor Gojong-Gwangmu promoted King Heonjong into Posthumous Emperor during the Foundation of the Korean Empire. Thus, King Heonjong granted his Posthumous Imperial Name, which is known as Emperor Heonjong Chegeon Gyegeuk Jungjeong Gwangdae Jiseong Gwangdeok Hong-un Janghwa Gyeongmun Wimu Myeong-in Cheolhyo, Emperor Seong of Korean Empire (헌종체건계극중정광대지성광덕홍운장화경문위무명인철효성황제(憲宗體健繼極中正光大至聖廣德弘運章化經文緯武明仁哲孝成皇帝).