King Injong, previously known as Crown Prince Cheon-yun (Hanja: 仁宗王 [天胤世子]; Born: 10 March 1515 – Died: 8 August 1545, Reigned: 1544–1545), born Yi Ho (이호/李峼), was the 12th king of the Joseon Dynasty of Korea. His father was King Jungjong, and his mother was Queen Janggyeong of Papyeong Yoon Clan, whose brother was Yun Im. As the firstborn, he became Crown Prince in 1520 and succeeded his father to the throne following Jungjong's death in 1544.
The young king was very ambitious, and tried to reform the government of the time that was rife with corruption, a legacy of the failed reforms during his father's reign. He rehabilitated Jo Gwang-jo and recruited Sarim scholars who turned away from politics after Gimyo Third Literati Purge of 1519. His maternal uncle Yun Im exercised great power during this period. However, Injong was too often ill and died in 1545, just one year after coming to the throne. Following his death, Yum Im was executed by Yun Won-Hyung in the Eulsa Fourth Literati Purge of 1545 when King Myeongjong (son of the ambitious Queen Munjeong) succeeded the throne.
Some historians believe that Injong was poisoned by the Smaller Yun faction, led by Yun Won-Hyung, to enable Injong's half-brother to ascend the throne. According to unofficial chronicles, there is a tale of Munjeong finally showing love for her "adoptive" son King Injong, after decades of polite indifference (in reality behind-the-scenes hatred).
As Injong went to pay his morning respects, Munjeong’s face started radiating with a smile only a mother could give to her child. Injong took it as a sign that the Queen Mother was finally acknowledging him as the king, and in particular as her own son. He ate the ddeok that his step-mother gave him, not knowing that it would be the beginning of the end. He fell ill slowly, not enough to create any suspicion, but quickly enough that historians would later pick up on the event. Three days passed before Injong mysteriously died (after only 9 months of rule).
Queen Munjong’s son became King Myeongjong, while Munjeong became Queen Regent. The chronicles also tell that Munjeong was frequently visited by spirits at night after Injong’s death. So disturbed was she that she moved her residence from Gyeongbok Palace to Changdeok Palace.
King Injong was buried at the Royal Tomb of Hyoreung (孝陵), part of the Seosamneung Royal Tomb Cluster in Wondang-dong san 37-1 beonji, Goyang DeogYang-gu, Gyeonggi Province. He was posthumously known as King Injong Yeongjeong Heonmun Uimu Jangsuk Heumhyo the Great (인종영정헌문의무장숙흠효대왕.仁宗榮靖獻文懿武章肅欽孝大王).