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The year he turned 19, he appeared in the film Kick the Moon. TenAsia says in a 2026 article that he debuted with this film. In 2005 he finished his military service and entered the broadcasting and entertainment department at Seoul Institute of the Arts.
The year he turned 27, he debuted in drama as Joong-ho in MBC’s Friend, Our Legend. Newsen and MHN Sports give this work as his debut. In 2010 he was cast as Heo Taek-woo, a national judo team athlete, in SBS’s Dr. Champ. In 2011 he took part in his first historical drama, Warrior Baek Dong-soo.
The breakthrough yearThe year he turned 30, he played Bang Sung-jae in tvN’s Reply 1997 and became known, three years after his debut.
In 2013 he made a special appearance in Reply 1994 as Bang Sung-jae. In 2014 he played Yoon Shin-joong in JTBC’s daily drama The Noblesse. In 2015 he played the cartoonist Shin Chung-jae in tvN’s Hogu’s Love.
The year he turned 34, he played Park Soo-bong in MBC’s W: Two Worlds, and in September he appeared on I Live Alone for the first time. In 2017 he received the Rookie Award at the MBC Entertainment Awards. In 2018 he received the Top Excellence Award (male) at the same ceremony.
The year he turned 38, he left I Live Alone, saying he wanted to focus on acting. In 2021 he married the actress Seo Ji-seung. In December 2022 he started MBC’s Adventure by Accident.
The year he turned 42, he made a special appearance in SBS’s Good Partner. In 2025 he appeared in Adventure by Accident 4 and received the Best Entertainer Award at the MBC Entertainment Awards. In 2026 he joined Netflix’s Bloodhounds season 2, and a son was born in May.
Lee Si-eon (born Jul 3, 1982) debuted in drama in 2009, the year he turned 27, with MBC’s Friend, Our Legend, and became known on Jul 24, 2012, the year he turned 30, when tvN’s Reply 1997 premiered with him as Bang Sung-jae. In 2017 he received the Rookie Award at the MBC Entertainment Awards.
TenAsia’s 2026 article says he debuted with this film. Newsen (2012) and MHN Sports (2026) give the 2009 drama as his debut.
Source 01 · TenAsia (Korean) · Lee Si-eon’s gift for his son · opens in a new tabSource 03 · Newsen (Korean) · Lee Si-eon interview · opens in a new tabSource 10 · MHN Sports (Korean) · Lee Si-eon reveals his son · opens in a new tab The year follows TenAsia’s 2026 article. The month, day and role were not confirmed in news reports.Entered the broadcasting and entertainment department after finishing his military service. He reportedly appeared on the theater stage from his first year.
Source 02 · Yonhap News Agency (Korean) · Reply 1997’s Lee Si-eon · opens in a new tabPlayed Joong-ho in the drama directed by Kwak Kyung-taek. His birth name is Lee Bo-yeon; the name Lee Si-eon was chosen for him by Kwak and the head of the production company, who went to a professional name-giver.
Source 04 · Newsis (Korean) · Friend, Our Legend ratings · opens in a new tabSource 05 · Newsen (Korean) · Friend, Our Legend episode 8 · opens in a new tabSource 03 · Newsen (Korean) · Lee Si-eon interview · opens in a new tab The month comes from the article on first-episode ratings (June 29); the day was not confirmed.Cast as a newcomer in the role of Heo Taek-woo, a national judo team athlete.
Source 06 · Newsen (Korean) · Dr. Champ casting · opens in a new tab The date is that of the article in which his agency announced the casting.Played Daeheung, a bodyguard of Crown Prince Sado, in episode 5. It was his first historical drama since his debut.
Source 07 · Maeil Business Newspaper (Korean) · Warrior Baek Dong-soo’s Lee Si-eon · opens in a new tab The date is the broadcast date of episode 5, as reported by Maeil Business Newspaper. The premiere date was not confirmed.Played Bang Sung-jae, a chatterbox who speaks in the Busan dialect. Newsen says he drew more attention with this drama, and TV Report says he was rediscovered and left a lasting impression on viewers.
Made a special appearance as Bang Sung-jae in episodes 16 and 17, aired on the 13th and 14th.
Source 11 · News1 (Korean) · Reply 1994 cameo · opens in a new tabPlayed Yoon Shin-joong, a son who comes home a week after being discharged from the military.
Source 12 · Seoul Economic Daily (Korean) · The Noblesse casting · opens in a new tabPlayed the cartoonist Shin Chung-jae and shared his comments on the finale on March 31.
Source 13 · Donga.com (Korean) · Hogu’s Love finale comments · opens in a new tab The finale date was not confirmed; the article with his comments is dated March 31.Played Park Soo-bong, an apprentice of Oh Seong-moo. Busan Ilbo says the role earned him the nickname “Extreme Job Soo-bong,” meaning Soo-bong with the grueling job.
Source 14 · OSEN (Korean) · W’s Park Soo-bong · opens in a new tabSource 15 · Busan Ilbo (Korean) · I Live Alone debut · opens in a new tab The date is the broadcast date of episode 9, as reported by OSEN. The premiere date was not confirmed.Appeared for the first time on that day’s broadcast and showed his life living alone.
Source 15 · Busan Ilbo (Korean) · I Live Alone debut · opens in a new tabReceived the Rookie Award for I Live Alone.
Source 16 · Joynews24 (Korean) · 2017 MBC Entertainment Awards · opens in a new tabReceived the Top Excellence Award in the male category.
Source 17 · Segye Ilbo (Korean) · 2018 MBC Entertainment Awards · opens in a new tabOn December 9 he announced his departure himself, saying he wanted to focus on acting. His last broadcast aired on the 25th.
Source 18 · Ilgan Sports (Korean) · Leaving I Live Alone · opens in a new tabHeld a small wedding on Christmas Day, attended only by family and relatives.
Source 19 · TenAsia (Korean) · Lee Si-eon and Seo Ji-seung marry · opens in a new tabA variety show following an unplanned trip through South America with Kian84 and Pani Bottle.
Source 20 · JTBC (Korean) · Adventure by Accident buzz ranking · opens in a new tabMade a special appearance as Kim Hoon, who runs a scam with his wife.
Source 21 · OSEN (Korean) · Good Partner special appearance · opens in a new tabAppeared in season 4, which aired in June.
Source 22 · TV Report (Korean) · Lee Si-eon’s New Year greeting · opens in a new tab The exact premiere date was not confirmed.Received the Best Entertainer Award in the male category.
Source 23 · Yonhap News Agency (Korean) · 2025 MBC Entertainment Awards · opens in a new tabJoined season 2 as a new cast member, playing Man-bae, a former National Intelligence Service agent turned broker. His agency confirmed the appearance in December 2025.
Source 24 · bnt News (Korean) · Lee Si-eon joins season 2 · opens in a new tabSource 25 · OSEN (Korean) · Agency confirms appearance · opens in a new tabA son was born to him and the actress Seo Ji-seung, five years after their marriage.
Source 26 · Sports Kyunghyang (Korean) · Lee Si-eon and Seo Ji-seung have a son five years after marrying · opens in a new tabEND OF SELECTED RECORDSSelected records, 2001–2026 · not a complete list of work. “Key moment” is an editorial label, not a measure of success.
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AgeTrail lines up the key moments of a life by age.
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Film & TV · South Korea
1982.07.03
Ages count from 1982 by year, birthdays aside. “Key moment” labels and the story that links the records are AgeTrail's own picks.
Fact-checked: 2026.10.12 · An independent archive, not affiliated with the person or their agency.