Isabella Romola de' Medici was a Tuscan noblewoman and the daughter of Cosimo I de' Medici, first Grand Duke of Tuscany, and Eleonora di Toledo. Beautiful, intelligent, witty and refined, she is often referred to as the Star of the House of Medici, in recognition of "her playfulness, vibrancy, often sarcastic sense of humour, sharpness and interest in a huge variety of topics - not to mention the great parties she held". She received a humanist education alongside her brother, Francesco de' Medici, who succeeded their father as the Grand Duke of Tuscany. To secure Tuscany's southern borders via a relationship with the powerful Roman Orsini family, Isabella's father arranged her marriage to Paolo Giordano I Orsini when she was 16. At her father's behest, she remained in Florence after her marriage, affording her an unprecedented level of independence for a woman of her era.

Cosimo I de' Medici was the second duke of Florence from 1537 until 1569, when he became the first grand duke of Tuscany, a title he held until his death.