* She was Grace Kelly's sister-in-law
Princess Antoinette of Monaco, Countess of Polignac, Baroness of Massy (Antoinette Louise Alberte Suzanne Grimaldi; December 28, 1920 – March 18, 2011) was a non-dynastic member of the princely family of Monaco and the elder sister of the late Prince Rainier III and aunt of Albert II, Prince of Monaco. Her parents were Prince Pierre, Duke of Valentinois and Princess Charlotte, Duchess of Valentinois.
Her brother, Prince Rainier III, was married to American actress Grace Kelly.
Princess Antoinette Cause of Death
On 18 March 2011 Princess Antoinette died in hospital, aged 90.
Princess Antoinette with her parents, brother and maternal grandfather.