"Paul is dead" is an urban legend and conspiracy theory alleging that English musician Paul McCartney of the Beatles died in 1966 and was secretly replaced by a look-alike. The rumour began circulating in 1966, gaining broad popularity in September 1969 following reports on American college campuses.

According to the theory, McCartney died in a car crash, and to spare the public from grief, the surviving Beatles, aided by Britain's MI5, replaced him with a McCartney look-alike, subsequently communicating this secret through subtle details of their albums. Proponents perceived clues among elements of Beatles songs and cover artwork; clue-hunting proved infectious, and by October 1969 had become an international phenomenon. Rumours declined after Life published an interview with McCartney in November 1969.

The phenomenon was the subject of analysis in the fields of sociology, psychology and communications during the 1970s. McCartney parodied the hoax with the title and cover art of his 1993 live album, Paul Is Live. The legend was among ten of "the world's most enduring conspiracy theories" according to Time in 2009.