Donald Sinclair may refer to:
Donald Sinclair (hotel owner) (1909–1981), inspiration for the television sitcom Fawlty Towers Donald Sinclair (veterinary surgeon) (1911–1995), inspiration for James Herriot's All Creatures Great and Small Donald Sinclair (Ontario politician) (1829–1900), Canadian politician Donald Sinclair (diplomat), former Canadian ambassador to Israel Donald Sinclair (American politician) (1899-1978), American farmer and politician