Last Night is a 2010 romantic drama film that was written and directed by Massy Tadjedin, her directorial debut. The film follows married couple Joanna (Keira Knightley) and Michael Reed (Sam Worthington), who are tempted by different forms of infidelity when they spend a night apart following a fight. Joanna is emotionally drawn to her ex-boyfriend Alex Mann (Guillaume Canet) while Michael is physically attracted to his co-worker Laura Nunez (Eva Mendes). The cast includes Griffin Dunne, Daniel Eric Gold, Anson Mount, Stephanie Romanov, Scott Adsit, Justine Cotsonas, and Chriselle Almeida. Last Night was produced by Entertainment One in association with the Gaumont Film Company, and deals with questions about emotional and physical infidelity.

The film was developed as a romance and suspense story before Tadjedin recognized its moral significance. After persuading Knightley to break a year-long acting hiatus to participate in the film, Tadjedin cast the other roles with consideration for the actors' chemistry. Mendes originally turned down the role of Laura but agreed to appear in the film after a conversation with Tadjedin. The soundtrack was composed by Clint Mansell, who received a World Soundtrack Award for Soundtrack Composer of the Year for his work.

Miramax Films initially bought Last Night for a March 19, 2010 release, but it was delayed by the company's sale to Filmyard Holdings. The film was shown at the 2010 Toronto International Film Festival and the 2010 Rome Film Festival. It premiered theatrically in France on February 16, 2011, and had a limited release in the United States on May 6, 2011. It was released through video on demand. Critics were divided over the film's plot and its commentary on infidelity; the performances from Knightley, Canet, and Mendes received praise while Worthington and the scenes between Michael and Laura were the subject of criticism. Last Night grossed $7.7 million, primarily from foreign markets.