Ryu Si Won was born on 6 October 1972. He is a South Korean actor and singer. After he made his debut in the KBS drama Feeling in 1994, Ryu pursued a singing career.
On 12 December 2004, Ryu went with a Taiwanese actress to Singapore for the presentation of the Star awards to Singaporean actors in the Mediacorp Star Awards 2004. The event was broadcast on Mediacorp's TV Channel 8.
Ryu revealed that he is the 14th-generation descendant of Joseon Dynasty Prime Minister, Yu Seong-ryong.
Ryu has studied photography for three years and has produced his own promo photos. Because of this, in 2009, he worked for the very first time with his co-actor Ko Soo and he is the man behind Ko's very first photo diary, "24 Hours with Ko Soo". It spans approximately 100 shots, which will be produced as a DVD. He also gives support to Ko for his career.
Subsequent to the broadcast of his 2001 drama Beautiful Days in Japan, he had been active there both as an actor and a singer. He was the first Korean artist to hold two live concerts at the Tokyo Dome, in December 2008. Then in November 2011, he held his 100th solo concert in Japan as part of his 16 concert tour in eight cities, including Yokohama, Nigata, Osaka, Sendai, Nagoya, and Fukuoka; with the final concert on 21 December at Saitama Super Arena.
On 21 December 2011, Ryu was signed on by Japanese travel agency H.I.S, for one-year to promotion Korean tourism in Japan. Where he was featured in two 15-second commercials in the themes of "Let’s go to Korea" and "You are the character of your drama" for Japanese television in January 2012.
In May 2012, Ryu starred in Channel A's drama Goodbye Dear Wife along with Hong Soo-hyun, Park Ji-yoon, Danny Ahn and Julien Kang. He played the role of judo teacher Cha Seung-hyuk who dreams of reuniting with his first love.