Seo Kang Joon

People search for his eye colour more often than for his age and his height put together, and most of the answers online state a cause as though it were settled. His own answer is on the record, and it is simpler than the theories.

On Shin Dong Yup's talk show Jjanhan Hyung on 17 February 2025, the host said his features are rarely seen in Korea. Seo Kang Joon replied that he wears no contact lenses, and that he and his older sister both have brownish eyes while their parents do not. He said the difference was pronounced enough that in high school he wondered whether he had been adopted, and made a joke of it on the show.

So: the colour is natural, he has said so himself, and the reason it photographs the way it does is that brown this light is uncommon in Korea and warm or direct light exaggerates it. That is why the effect is strong in some dramas and almost invisible in others. The older profiles that call it dark brown are describing the wrong thing, and the ones that credit coloured lenses are contradicted by the man himself.

5urprise was put together by Fantagio out of five people recruited through the company's Actor's League, its scheme for finding new actors, and trained for roughly two years in acting, dance and singing. Fantagio announced the line-up on 8 August 2013 and billed it as Korea's first five-man actor group. What made it unusual was the order of things: the group was introduced through a drama rather than a stage. Its first work was the mobile dramatoon After School: Lucky or Not, which began on 2 September 2013 across SK Planet's mobile channels (Nate, Hoppin, T-store and Btv), with its OST track Hey U Come On issued days earlier. Yoo Il put the intent plainly that month: they were actors first who would also take on singing and dancing, the reverse of an idol group. That explains the shape of Seo Kang Joon's early career better than any talent narrative. He was being promoted as a face and cast as a performer in the same year, which is why he went from a 2012 bit part to two leading roles by the end of 2013.

The line-up was Seo Kang Joon, Gong Myung, Kang Tae Oh, Lee Tae Hwan and Yoo Il. There was never a disbandment announcement. What Fantagio confirmed was that all five exclusive contracts had ended on 31 March 2020, and SBS reported it the next day under a headline calling it a break-up after seven years, with the company framing it as each actor taking his own path. Four of them signed with Man of Creation together on 8 April 2020: Seo Kang Joon, Kang Tae Oh, Lee Tae Hwan and Yoo Il. They followed their long-time manager there rather than moving to a larger agency.

Are You Human? in 2018 asked him to play Nam Shin and the android built in his image, in scenes where the other characters cannot tell them apart. It is the clearest test of what he does well. The difference between the two is carried almost entirely in stillness rather than in dialogue, and the drama only works if the audience can tell them apart before the characters can.

KBS gave him two awards for it that December: the Excellence Award for an actor in a mid-length drama, and Best Couple with Gong Seung Yeon.

It also gave him his only solo release. He recorded You Are My Love for the drama's soundtrack, put out on 7 August 2018 as Part 9, singing it in the voice of the android; the music director said afterwards that nobody had expected him to sing.

He enlisted for active duty in the Army on 23 November 2021 and was discharged on 22 May 2023, serving the full eighteen month term. It landed at the point in a career where absence usually costs most, and it is the reason readers searching for him in 2022 and 2023 kept finding nothing new.

He finished recruit training first of the 150 trainees in his intake at the Army's 3rd Infantry Division training centre, and was given a division commander's commendation at the graduation on 29 December 2021. He served the rest of his term as a driver.

His return was Undercover High School, which ran on MBC from 21 February to 29 March 2025 over twelve episodes and was his first work in about three years. He plays a National Intelligence Service agent who goes back into a school uniform to trace Emperor Gojong's missing gold. On 30 December 2025 MBC gave him the Grand Prize at its drama awards, the highest honour the broadcaster hands out in a year and the first Daesang of his career. The series took Drama of the Year on the same night.