Transformers: Revenge of the Fallen is a 2009 American science fiction action film based on Hasbro's Transformers toy line. The film is the second installment in the Transformers film series and a sequel to Transformers (2007). The film is directed by Michael Bay and written by Ehren Kruger, Roberto Orci, and Alex Kurtzman. Set two years after the events of Transformers, Revenge of the Fallen recounts the battle between the Autobots, led by Optimus Prime (voiced by Peter Cullen), and the Decepticons, led by Megatron (voiced by Hugo Weaving). The Autobots and Sam Witwicky (Shia LaBeouf) ally again to face an ancient Decepticon named the Fallen (voiced by Tony Todd), who pursues revenge on Earth.

Development on a sequel to Transformers began by May 2007. With deadlines jeopardized by possible strikes by the Directors Guild of America and the Screen Actors Guild, Bay managed to finish the production on time with the help of previsualization and a scriptment. Shooting took place between May and September 2008, with locations in Egypt, Jordan, Pennsylvania, New Jersey, and California, as well as air bases in New Mexico and Arizona.

It premiered on June 8, 2009, at Roppongi Hills in Tokyo, Japan and was released on June 24 in the United States. The film received generally negative reviews from critics. It won three Golden Raspberry Awards at the 30th Golden Raspberry Awards ceremony and became the highest-grossing film to win the Worst Picture award at the time. The film surpassed its predecessor's box office gross worldwide with $836.5 million, making it the fourth-highest-grossing film of 2009. It was nominated for the Academy Award for Best Sound Mixing, at the 82nd Academy Awards. With over 11 million home media sales in 2009, it was also the top-selling film of the year in the United States. It was followed by Transformers: Dark of the Moon in 2011.