Dad's Army is a British television sitcom about the United Kingdom's Home Guard during the Second World War. It was written by Jimmy Perry and David Croft, and originally broadcast on BBC1 from 31 July 1968 to 13 November 1977. It ran for nine series and 80 episodes in total; a feature film released in 1971, a stage show and a radio version based on the television scripts were also produced. The series regularly gained audiences of 18 million viewers and is still shown internationally.

The Home Guard consisted of local volunteers otherwise ineligible for military service, either because of age (hence the title Dad's Army), medical reasons or by being in professions exempt from conscription. Most of the platoon members in Dad's Army are over military age and the series stars several older British actors, including Arnold Ridley, John Laurie, Arthur Lowe and John Le Mesurier. Younger members of the cast included Ian Lavender, Clive Dunn (who, despite being one of the younger cast members, played the oldest guardsman, Lance Corporal Jones) and James Beck (who died suddenly during production of the sixth series in 1973). Other regular cast members included Frank Williams as the vicar, Edward Sinclair as the verger, and Bill Pertwee as the chief ARP warden. Following the death of Lavender in 2024, there are now no surviving principal cast members.

The series has influenced British popular culture, with its catchphrases and characters being widely known. The Radio Times magazine listed Captain Mainwaring's "You stupid boy!" among the 25 greatest put-downs on TV. A 2001 Channel 4 poll ranked Captain Mainwaring 21st on its list of the 100 Greatest TV Characters. In 2004, Dad's Army came fourth in a BBC poll to find Britain's Best Sitcom. It was placed 13th in a list of the 100 Greatest British Television Programmes, drawn up by the British Film Institute in 2000, and voted for by industry professionals. A second feature film of Dad's Army with a different cast was released in 2016.

In 2019, UKTV recreated three missing episodes for broadcast in August that year on its Gold channel under the title Dad's Army: The Lost Episodes. It starred Kevin McNally and Robert Bathurst as Captain Mainwaring and Sergeant Wilson.