On Her Majesty's Secret Service is a 1969 spy film and the sixth in the James Bond series produced by Eon Productions. It is based on the 1963 novel by Ian Fleming. Following Sean Connery's decision to retire from the role after You Only Live Twice, Eon selected George Lazenby, a model with no prior acting credits, to play the part of James Bond. During filming, Lazenby announced that he would play the role of Bond only once. Connery returned to portray Bond in 1971's Diamonds Are Forever.

In the film, Bond faces Blofeld (Telly Savalas), who is planning to hold the world to ransom by threatening to render all food plants and livestock infertile through the actions of a group of brainwashed "angels of death". Along the way Bond meets, falls in love with, and eventually marries Contessa Teresa di Vicenzo (Diana Rigg).

It is the only Bond film to have been directed by Peter R. Hunt, with this serving as his directorial debut, who had served as a film editor and second unit director on previous films in the series. Hunt, along with producers Albert R. Broccoli and Harry Saltzman, decided to produce a more realistic film that would follow the novel closely. It was shot in Switzerland, England, and Portugal from October 1968 to May 1969. Although its cinema release was not as lucrative as its predecessor You Only Live Twice, On Her Majesty's Secret Service was still one of the top-performing films of the year. Critical reviews upon release were mixed, but the film's reputation has improved greatly over time and it is now regarded as one of the strongest entries in the series as well as one of the most faithful adaptations of a Fleming novel. The title of the book and film is a play on the phrase "On Her Majesty's Service".