Sir John Hegarty (1944-) is an advertising executive and a founder of the agency Bartle Bogle Hegarty.
He joined Cramer Saatchi in 1967, and was a founding shareholder when it became Saatchi & Saatchi. In 1973 he co-founded TBWA, and then in 1982 started Bartle Bogle Hegarty.
He appeared as a "castaway" on the BBC Radio programme Desert Island Discs on 23 June 1991, and was knighted for his services to the advertising and creative industries in 2007.