Princess Tatiana Maria Renata Eugenia Elisabeth Margarete Radziwiłł na Nieświeżu h. Trąby (born 28 August 1939) is a French-Polish aristocrat, bacteriologist, and nurse. The eldest daughter of Prince Dominik Rainer Radziwiłł and Princess Eugénie of Greece and Denmark, she is a member of the House of Radziwiłł and a close relative to the Greek, Danish, and Spanish royal families. She served as a bridesmaid at the Wedding of Prince Juan Carlos of Spain and Princess Sophia of Greece and Denmark in 1962 and at the wedding of Constantine II of Greece and Princess Anne-Marie of Denmark in 1964. She has remained a close friend and courtier of her cousin, Queen Sofía of Spain.