Isabella Romola de' Medici (31 August 1542 – 16 July 1576) was the daughter of Cosimo I de' Medici, first Grand Duke of Tuscany, and Eleonora di Toledo. She received a humanist education alongside her brother, Francesco de' Medici, who succeeded their father as the Grand Duke of Tuscany. To secure a relationship with the powerful Roman Orsinis, Isabella's father arranged her marriage to Paolo Giordano I Orsini when she was 16. She remained in her father's household after her marriage, giving her an unusual degree of independence for a woman of her period. Following the death of her father, Isabella was murdered, with the complicity of her husband and brother, and in retribution for her relationship with Paolo Giordano's cousin Troilo Orsini.