Dame Sibyl Mary Collings Beaumont Hathaway DBE (1884-1974) was Dame of Sark from 1927 until her death in 1974. Her 47-year rule over Sark, in the Channel Islands, spanned the reigns of four Monarchs and during her lifetime Sark probably experienced more danger and excitement than in the whole of the rest of its history.

Sark, a remnant of the ancient Duchy of Normandy is one of the Channel Islands and one of the oldest possessions of the British Crown, . Since the days of Queen Elizabeth I it has been the possession of a feudal chief known as the Seigneur-or, in the case of a woman, the Dame.

Dame Sibyl's tenure saw the German occupation of the Channel Islands in the Second World War, during which she refused to evacuate and convinced the islanders to stay as well. Her eldest son and heir apparent, Francis William Beaumont, was killed in 1941, while her husband was deported to an internment camp in 1943.

The Dame remains best known for her indomitable conduct during the occupation. After the war, she continued her publicity campaign, strengthening the island's tourism industry. She was described by a British government official as a "lady of unusual personality", and is often referred to as a benevolent dictator. Dame Sibyl died at the age of 90, and was succeeded by her grandson, Michael Beaumont.

The Dame of Sark is an unparalleled figure in the modern scene, and her beloved non-conforming island is like nowhere else in the world. She tells the story of her life and of her unique domain with characteristic forthrightness and a mischievous sense of humour.