Most wanted: celebs investigated by the FBI
Marilyn Monroe - Marilyn Monroe was investigated because of her marriage to Arthur Miller, who was a suspected communist.
R. Kelly - In response to rampant allegations of abuse, R. Kelly was investigated by the FBI.
Princess Diana - Diana's file is pretty brief, but does mention death threats against her, and a planned trip to New York City that was met with protests.
Ryan Adams - According to reports, the FBI opened an inquiry into Ryan Adams, after reports that he allegedly engaged in sexual activities with a teenager.
Walt Disney - Walt Disney actually worked as a FBI informant during the McCarthy era. In return, the Bureau let Disney film 'The Mickey Mouse Club' at the FBI HQ.
Anna Nicole Smith - Smith was investigated for an alleged murder plot on her late husband's son, who she battled with over inheritance. However, there wasn't enough evidence to charge her.
Shakur -
2Pac is one the most famous rappers with an FBI file. He was investigated for death threats that he allegedly received from the Jewish Defense League.
Grace Kelly - The actress-turned-princess was briefly investigated, after she invited the FBI Director to a gala and banquet.
John Lennon - John Lennon was an active political figure, with strong anti-war messages that resonated with people around the world. The FBI attempted to revoke Lennon's visa.
Helen Keller - The deaf blind pioneer was heavily investigated for her socialist beliefs, support of birth control, and her co-founding of the American Civil Liberties Union.
John Denver - The FBI thought Denver's drug use, and appearance at an anti-war rally, were quite fishy. He was also investigated for death threats that he received.
Jackie Robinson - Jackie Robinson was more than a baseball player. He was also involved in the Civil Rights movement, which the FBI found to be pretty suspicious.
The Kingsmen - The Kingsmen scored a hit with 'Louie Louie,' which features hard-to-discern lyrics. The FBI got suspicious, and investigated the song and band.