LONDON—Stella Tennant, the aristocratic British model who was a muse to designers such as Karl Lagerfeld and Gianni Versace, has died suddenly at the age of 50, her family said Wednesday. Tennant, the granddaughter of a duke, rose to fame in the 1990s while walking the runway for designers including Versace and Alexander McQueen. In a statement, her family said: “It is with great sadness we announce the sudden death of Stella Tennant on Dec. 22.” “Stella was a wonderful woman and an inspiration to us all. She will be greatly missed,” it said. The family asked for privacy and said arrangements for a memorial service would be announced later. Police Scotland said officers were called to an address in the Scottish Borders town of Duns on Tuesday following the sudden death of a 50-year-old woman. Police said there were no suspicious circumstances. The granddaughter of the 11th Duke of …