Nigel Richard Patton Dempster (1 November 1941 in Calcutta, India – 12 July 2007 in Ham, Surrey) was a British journalist, author, broadcaster and diarist. Best known for his celebrity gossip columns in newspapers, his work appeared in the Daily Express and Daily Mail and also in Private Eye magazine. At his death, the editor of the Daily Mail Paul Dacre was reported as saying: "His scoops were the stuff of legend and his zest for life inexhaustible".

The son of an Australian mining engineer, who was fifty when Dempster was born, and an English mother, he was educated at Sherborne School in Dorset. After gaining three O-levels, he was ultimately expelled at 16 for being a "disruptive influence" after several misdemeanours.

After short periods working in the City and in public relations, Dempster joined the Daily Express in 1963 and remained at the title until 1971. Here he was a contributor to the 'William Hickey' column, and used his contacts to gain stories about the aristocracy and other public figures. He was then on the staff of the Daily Mail from 1971 to 2003, where he was initially deputy to Paul Callan, but replaced him as the newspaper's diarist in 1973. While Dempster was sometimes inaccurate, for instance dismissing suggestions that Prince Charles would marry Lady Diana Spencer, he forecast in 1975 that Harold Wilson would soon resign as Prime Minister, three months before he did so in 1976. Supposedly this took everyone by surprise, but a contact of Dempster's had overheard the Foreign Secretary James Callaghan discussing it. Dempster was also close to Princess Margaret, despite breaking news of her liaison with Roddy Llewellyn.