Bianca Cappello was an Italian noblewoman, the Grand Duchess consort of Tuscany by marriage to Francesco I de' Medici, Grand Duke of Tuscany. She was Francesco's mistress that later married him to became his consort. Coincidentally, the creation of the fortunate term serendipity by the writer Horace Walpole is due to a portrait of Bianca.

Francesco I was the second Grand Duke of Tuscany, ruling from 1574 until his death in 1587. He was a member of the House of Medici.