Live Free or Die Hard (released as Die Hard 4.0 outside North America) is a 2007 American action thriller film directed by Len Wiseman, and serves as the fourth installment in the Die Hard film series. It is based on the 1997 article "A Farewell to Arms" written for Wired magazine by John Carlin. The film's name references New Hampshire's state motto, "Live Free or Die".

In the film, NYPD Detective John McClane (Bruce Willis) attempts to stop a cyber-terrorist, Thomas Gabriel (Timothy Olyphant) who hacks into government and commercial computers across the United States with the goal of starting a "fire sale" cyber attack that would disable key elements of the nation's infrastructure. Justin Long, Cliff Curtis, Maggie Q, and Mary Elizabeth Winstead also star.

Live Free or Die Hard was released in the United States on June 27, 2007. The film grossed $388 million worldwide, making it the highest-grossing installment in the Die Hard series. It received positive reviews from critics. It is the only Die Hard film to be theatrically released with a PG-13 rating from the MPAA, although an unrated edition would later be made available on home media. A fifth film, A Good Day to Die Hard, was released in 2013.