Pan-jungchubusa under Seonjo and Injo; pen name Yakbong; posthumous name Chungsuk; one of the seven ministers entrusted by Seonjo's will
Same-name figures:
서성(徐晟) — Judge who topped the first bar examination and served as Supreme Court justice and head of the Court Administration

| Life | 1558 ~ 1631 |
| Era | 조선 중기 |
| Clan | 대구 서씨 |
Seo Seong (1558-1631) was a mid-Joseon civil official of the Daegu Seo clan. Courtesy name Hyeongi, pen name Yakbong, posthumous name Chungsuk, he was a fourth-generation descendant of Seo Geo-gwang, elder brother of Seo Geo-jeong, and a son of Seo Hae, born at his maternal home in Andong. He lost his father within a year of birth and grew up in Hanyang at the house of his father's elder brother Seo Eom; his mother, of the Goseong Yi, is remembered as a model mother who raised him alone.
He studied under Yi I and Song Ik-pil and became a Westerner. Passing the civil examination under Seonjo, he began as Vice Director of the Ministry of Military Affairs. When the Imjin War broke out he escorted the king in flight, later serving as secret inspector, royal secretary, governor of Gyeongsang, Gyeonggi, Gangwon, Pyeongan and Hamgyeong provinces, then Inspector-General and minister in several ministries. He is said to have been one of seven ministers asked at Seonjo's deathbed in 1608 to protect Grand Prince Yeongchang.
Implicated in the 1613 Gyechuk incident under Gwanghaegun, he was exiled for eleven years and restored after the 1623 Restoration, escorting Injo during the Yi Gwal rebellion and the 1627 Manchu invasion. In 1628 he was named a first-class Yeongsa wonjong merit subject for helping suppress the Yu Hyo-rip revolt, and rose to Pan-jungchubusa. He formed the Namji Girohoe with Yi In-gi and Yi Gwi to discuss the Book of Changes, was skilled in calligraphy and painting, and left the Yakbong-jip. His four sons each founded a major line, and he is regarded as a central figure in the clan's flourishing.
He lost his father Seo Hae within a year of birth and grew up at the house of his father's elder brother Seo Eom in Hanyang, then studied under Yi I and Song Ik-pil. His mother of the Goseong Yi is introduced as a model mother who moved to Hanyang to educate him.
Implicated in the Gyechuk incident under Gwanghaegun, he was exiled for eleven years and restored after the Restoration. He and his son Seo Gyeong-ju are said to have opposed deposing Queen Dowager Inmok.
His tomb (Gyeonggi Monument No. 35) and Sangsimjeongji (Yangpyeong Local Heritage No. 44) remain, and his collected works, the Yakbong-jip, survive.
Seo Seong's tomb is in Seorun-dong, Pocheon, Gyeonggi, designated Gyeonggi Monument No. 35 in 1976. Sangsimjeongji in Yangpyeong is listed as Yangpyeong Local Heritage No. 44.
His sons Seo Gyeong-u (Mansa-gong), Seo Gyeong-su (Jeoncheom-gong), Seo Gyeong-bin (Cheomchu-gong) and Seo Gyeong-ju (Dowi-gong) founded the main lines, from whom chief state councillors and chief academicians followed.