Concubine-turned-wife of Yun Won-hyeong in the Queen Munjeong era; known also for proposing eased discrimination against secondary sons and introducing the monk Bou, though assessments are divided

| Life | 1506 ~ 1565 |
| Era | 조선 중기 |
| Clan | 초계 정씨 |
Jeong Nan-jeong (鄭蘭貞, 1506-1565), of Chogye, was born in Hanseong. Her father was Jeong Yun-gyeom, deputy commander of the Five Garrisons; her mother is said to have been a servant of the household, a concubine née Nam whose name is not recorded. She was the youngest of two sons and three daughters and is said to have left home young and become a courtesan, but this rests on later tradition.
Noticed by Yun Won-hyeong, brother of Queen Munjeong, she became his concubine, and after his first wife, née Kim of Yeonan, was expelled following the Kim An-ro affair she effectively ran the household. In 1553 (Myeongjong 8) the queen's order made her his legitimate wife, with the rank Lady Jeonggyeong of the first senior rank. She is said to have entered the palace freely and amassed wealth by controlling trade. Records say four sons and two daughters.
She is known for urging the queen to employ capable sons and daughters of secondary wives, and records say secondary sons were afterwards allowed to seek office. She also introduced the monk Bou to the queen, which revived the Seon and Gyo orders and the monk certificate system for a time (sources disagree whether Bou held the post of Seonjong head or Minister of Military Affairs). After the queen's death in 1565, scholar-officials impeached the couple, and Yun's stepmother née Kang accused her of poisoning Yun's first wife. Reduced to commoner status and on her way into exile in Gangeum, Hwanghae, she is said to have drunk poisoned wine and died on 13 November; Yun followed.
The literati faction called her the embodiment of a wicked woman, an image carried on in anecdote, folktale, plays and dramas. Others view her proposal to ease discrimination against secondary sons as a challenge to the status system at the time. The poisoning charge is a recorded accusation, not an established fact, and the story that she died by royal poison is read as a later legend reflecting the literati's grievance. This entry places the recorded facts and differing views side by side rather than judging.
She is said to have been buried near the family hill in Gyoha (Danghadong), Paju, Gyeonggi; the stele before the tomb was reportedly raised only after the fall of Joseon.