After the 38th parallel line was drawn across Korea, he and his family moved to Paju on the South Korean side controlled by the U.S. Army.

[5] He was a member of the National Theater Company of Korea from 1987 to 2010, where he worked with actors such as Jang Min-ho,[6] whom he considers his mentor.

[7] Throughout his career, he did productions of A Confession for a Black Prostitute (흑인 창녀를 위한 고백, Albert Camus's play adaptation of the novel Requiem for a Nun by William Faulkner[8]), A Streetcar Named Desire, and The Merchant of Venice, among many others.

[13] In January 2022, he won the Golden Globe Award for Best Supporting Actor, Television for his role in the series.

"[16] O has a daughter who, as he lacked an agent, helped him handle the volume of calls asking him to appear in various roles following Squid Game.

[20] He was accused of various cases of sexual misconduct in which he had inappropriately hugged, made lewd comments towards, laid in the same bed with, and kissed the victim across multiple incidents.

[22] A month later, he was found guilty and was sentenced to an eight-month suspended prison term, as well as being ordered to attend 40 hours of classes on sexual violence.