Donald William Sinclair was the co-proprietor of the Gleneagles Hotel in Torquay, Devon, England. 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.

The Gleneagles Hotel was a hotel in Torquay, Devon, England. The 41-bed establishment, which opened in the 1960s, was the inspiration for Fawlty Towers, a British situation comedy first broadcast in the mid-1970s. John Cleese, and his then wife Connie Booth, were inspired to write the series after they had stayed at the hotel and witnessed the eccentric behaviour of its co-owner, Donald Sinclair, who ran the hotel with his wife, Beatrice, until they sold it in 1973. Later the hotel was managed by Best Western. In February 2015 the hotel closed. It has since been demolished and replaced by retirement apartments.