So-sŏn Yi

Lee So-sun (; 1929 – 3 September 2011) was a South Korean labor activist. She became a labor activist after her son Jeon Tae-il, a sewing worker and labor activist, committed suicide by self-immolation in protest of the poor working conditions. She has been described as the "mother of laborers" for her activism.

Early life Lee So-sun was born in 1929 in the village of Dalseong-gun in Korea under Japanese rule. Her father was a farmer and was executed by Japanese colonial officers when she was four.

Lee had four children. Lee became a labor activist after Jeon's death, promising to Jeon on his deathbed to continue his work as a labor activist. In 1979, Lee helped found the Cheonggye Garment Workers' Union.

On May 4, 1980, Lee participated in protests at the Korea University library in Seongbuk-gu, Seoul, where she promoted the Cheonggye Clothing Workers' Union and decried the poor conditions for workers at Pyeonghwa Market. On May 9, 1980 she held a protest at the Federation of Korean Trade Unions Hall in Yeongdeungpo-gu, where she was arrested and charged with illegal assembly. In 1986, she helped found the Korean Association of Bereaved Families for Democracy and served as its first president.

In 2008, author Oh Do-yeop published To Those I Can't Thank Enough: Lee So-sun's Memory of 80 Years, a book written during two years of conversations between Lee and Oh.

Death and legacy Lee was hospitalized in July 2011 due to heart issues. A funeral was held at Seoul National University Hospital, with around 500 people in attendance, including actor and politicians Chung Dong-young, Lee Jung-hee, and Roh Hoe-chan. Directory Tae Joon-sik released , a documentary on Lee's life, in 2012. Lee was voiced by Yeom Hye-ran in the 2021 animated film Chun Tae-il: A Flame That Lives On.

In 2024, Lee was posthumously acquitted for violating martial law provisions in 1981 after a retrial request was filed in 2021.