Silmido (Korean: 실미도) is a 2003 South Korean action drama film directed by Kang Woo-suk. It is based on the 1999 novel Silmido by Baek Dong-ho, which in turn is based on the true story of Unit 684. Some parts of the film are dramatizations, as the actual details of certain events remain unknown. The film was both critically well received and a financial success, and was the first film in South Korea to attract a box office audience of over 10 million viewers.

209th Detachment, 2325th Group, commonly known as Unit 684 (684부대), was a black operations unit of the Republic of Korea Air Force formed to assassinate North Korean leader Kim Il Sung in 1968, in retaliation for the Blue House raid. The unit consisted of 31 civilian recruits, mostly petty criminals and unemployed youths, and underwent three years of harsh training on the island of Silmido. The assassination mission was cancelled in 1971 and the unit mutinied, resulting in a firefight in Seoul in which most of the members of the unit were killed. The four survivors were sentenced to death by a military tribunal and executed.