Lady Vengeance (Korean: 친절한 금자씨; RR: Chinjeolhan Geumjassi; lit. 'Kind Miss Geum-ja'; titled Sympathy for Lady Vengeance in Australia and Russia) is a 2005 South Korean neo-noir psychological thriller film directed by Park Chan-wook. The film is the third and final installment in Park's Vengeance Trilogy, following Sympathy for Mr. Vengeance (2002) and Oldboy (2003). It stars Lee Young-ae as Lee Geum-ja, a woman released from prison after serving the sentence for a murder she did not commit. The film tells her story of revenge against the real murderer.

The film debuted on 29 July 2005 in South Korea, and competed for the Golden Lion at the 62nd Venice International Film Festival in September 2005. While it failed to win in competition, it did walk away with Cinema of The Future, the Young Lion Award, and the Best Innovated Film Award in the non-competition section. It won the award for Best Film at the 26th Blue Dragon Film Awards. The film had its US premiere on 30 September 2005 at the New York Film Festival. It began its limited release in North American theatres on 5 May 2006, to favorable reviews from critics.

A Christian musical procession waits with a symbolic block of tofu outside a prison for the release of Lee Geum-ja, a reformed female prisoner. Convicted of kidnapping and murdering a 5-year-old schoolboy, Won-mo, 13 years earlier, Geum-ja became a national sensation because of her youth, saintly appearance, and willing confession to the crime. However, she became an inspirational model for prisoner reform during her incarceration, and her supposed spiritual transformation earned her an early release. Now free, she is intent on revenge.

Geum-ja quickly reveals that her "kind-hearted" behavior in prison was a cover to earn favor and further her revenge plans. She visits the other paroled inmates, calling in favors that include food, shelter, and weapons. She begins work in a pastry shop and gets involved with a young shop assistant, Geun-Shik, who would be the same age as Won-mo if he had lived.

It is revealed that Geum-ja did not smother Won-mo. The detective on her case was aware of her innocence, but helped her fake crime-scene details to ensure her confession looked credible. As a young high school student, Geum-ja had become pregnant and, afraid to go home to her parents, turned to Mr. Baek, a teacher at her school, for help. Mr. Baek expected Geum-ja to provide sex and assist in his kidnapping racket in return. He used her to lure 5-year-old Won-mo to him, with the intent of ransoming the child, but instead murdered him. He then kidnapped Geum-ja's infant daughter and threatened to murder the baby if Geum-ja did not take the blame. She spent her prison sentence plotting her revenge on Mr. Baek for the murder of Won-mo, for causing her child to grow up without a mother, and for sending her to prison.

Geum-ja discovers that her daughter was adopted by Australian parents. Jenny, now an adolescent, does not speak Korean and is initially resistant to her mother's outreach, though she does return with Geum-ja to Seoul to bond. Geum-ja plans to kidnap and murder Mr. Baek, now a children's teacher at a preschool, with the aid of his wife, another ex-convict. Mr. Baek hires thugs to kill Geum-ja and Jenny but Geum-ja kills them and Mr. Baek is subdued.

Mr. Baek wakes up tied to a chair in an abandoned schoolhouse. On his cell phone strap, Geum-ja discovers the orange marble from Won-mo's crime scene, which had been taken as a trophy, and is horrified to see other children's trinkets also on the strap. After shooting him in both feet, she discovers snuff tapes in his apartment of the other children he had murdered. He had not been part of a ransoming racket; he would kidnap and murder a child from each school he worked at because he found them annoying. After killing each one, he would fake a ransom call to the parents, collect the money, and move on to a different school.

Sickened that four more children died because Geum-ja did not turn in the real killer 13 years ago, Geum-ja and the original case detective contact the parents and relatives of the missing children and they meet at the school. After watching each tape, the group decides to murder Mr. Baek together. They take turns beating, mutilating and torturing him until he is dead, then take a group photo, ensuring that none of them can turn in the others without implicating themselves. They then bury the corpse outside.