Donald Sinclair, English lieutenant and businessman (d. 1981)
Donald William Sinclair (10 July 1909 – 1981) was the co-proprietor of the Gleneagles Hotel in Torquay, Devon, England, United Kingdom. He helped manage the hotel after an extensive career as an officer in the Merchant Navy and the Royal Navy. During the Second World War, Sinclair twice survived the sinking of the ships on which he was serving.

Sinclair is primarily known for being the inspiration for the character Basil Fawlty, played by John Cleese, in the television sitcom Fawlty Towers that Cleese co-wrote. This was owing to Sinclair's allegedly stuffy, snobbish and eccentric treatment of his guests, including Cleese and other members of the Monty Python cast. Cleese later played a character named Donald Sinclair in the 2001 film Rat Race.