Founder of the Yeosan Song clan; said to have been a Goryeo jinsa enfeoffed as Lord of Yeosan

| Era | 고려 |
| Clan | 여산 송씨 |
Song Yu-ik (宋惟翊) is honored as the founder of the Yeosan Song clan (礪山 宋氏), a Goryeo-era figure. Sources say that, as a jinsa degree holder, he rendered service to the state and was enfeoffed as Lord of Yeosan, and that after his death he was posthumously granted the rank of Eunchong Gwangnokdaebu and the post of Chumilwon busa. His dates of birth and death are not known.
The genealogy traces his ancestry to Song Ju-eun (宋周殷), a native of Gyeongjo in China who served as Minister of Revenue under the Tang, counting Song Yu-ik as his 11th-generation descendant. But Wikipedia and others note that Song Ju-eun does not appear in the official Tang histories and cannot be verified, so the pre-founder lineage is best read as clan tradition.
The seat Yeosan is today Yeosan-myeon in Iksan, North Jeolla, on the border with South Chungcheong. The clan holds that Song Yu-ik, Song Cheon-ik and Song Mun-ik, sons of Song Ja-yeong, founded the Yeosan, Eunjin and Seosan Song clans respectively, but newspaper reports point out that no evidence for this exists apart from the Yeosan Song genealogy itself. The line from the founder to the "middle founder" Song Song-rye is said to span four generations.
Yeosan (礪山) was formed from the old Yeoryang and Nangsan counties. Sources differ on when: some record the renaming to Yeosan-hyeon in 1399, others the merger of the two counties in 1402 (Taejong 2). Yeoryang was raised to a county in 1436 (Sejong 18) because it was the maternal home of Queen Wongyeong, consort of King Taejong, and it was merged into Iksan in the 1914 reorganization of districts.
The location of his tomb could not be confirmed. A clan ancestral hall is said to stand in Yeosan-myeon, the seat of the clan.
His descendants continue through his fourth-generation descendant Song Song-rye into five branches (Wonyun-gong, Miljik-gong, Soyun-gong, Jisin-gong and Jeongga-gong), and the 2015 census counted 298,231 members.