Before the Devil Knows You're Dead is a 2007 American crime thriller film directed by Sidney Lumet. The film was written by Kelly Masterson, and stars Philip Seymour Hoffman, Ethan Hawke, Marisa Tomei, and Albert Finney. The title comes from the Irish saying: "May you be in heaven a full half-hour before the devil knows you're dead". The film unfolds in a nonlinear narrative, repeatedly going back and forth in time, with some scenes shown repeatedly from differing points of view. It was the last film directed by Lumet before his death in 2011.

The film appeared on 21 critics' end-of-the-year top ten lists indexed by Metacritic and was selected as one of 2007's ten most influential American films by the American Film Institute, at the 2007 AFI Awards.