From one of the richest and noblest Venetian families, she was famed for her great beauty. At the age of fifteen she fell in love with Pietro Bonaventuri, a young Florentine clerk in the firm of Salviati, and on November 28, 1563 escaped with him to Florence, where they were married and in 1564 she had a daughter named Virginia. The Venetian government made every effort to have Bianca arrested and brought back; but the Grand Duke Cosimo di Medici intervened in her favour. She used her beauty to marry Francesco di Medici. She and Francesco died the same day. A forensic test in 2007 showed evidence of arsenic poisoning.
Her Wikipedia article is here.