Director, screenwriter and actor. Without real formal education, Ryoo started making short films in mid 1990’s (Transmutated Head, 1996; Dachimawa lee, 1998). He wrote and directed his first feature low budget film Jukgeona hokeun nabbeugeona (Die Bad, 2000).Thanks to the success of his first film, his next one, Pido nunmuldo eobshi (No Blood No Tears, 2002), was made with a bigger budget. Still faithful to the action genre, he made Arahan jangpung daejakjeon (Arahan, 2004). Afterwards he directed the sport drama Jumeogi unda (Crying Fist, 2005). He participated in the omnibus of Korean directors Daseot gae ui shiseon (If You Were Me 2, 2006), and on his own he made The City of Violence (Jjakpae, 2006). In 2008, he made one of his earlier short films into a long feature film titled Dachimawa Lee (Crazy Lee). He achieved the highest ratings with his crime thriller Boo-dang-geo-rae (The Unjust, 2010) and the spy thriller The Berlin File (2013).