Bianca Cappello

An exceptional Venetian beauty, Bianca eloped to Florence in 1563 with Pietro Bonaventura, a humble bankers’ clerk, an impetuous act of love that called down the full fury of the unsentimental Senate. The young couple were sentenced to death in absentia, and forgotten until it was discovered that Bianca had abandoned her clerk in favour of a much more palatable catch: the Grand Duke of Tuscany, Francesco de’ Medici, who ignored his dumpy Habsburg duchess for Bianca's more dazzling charms.

Diplomacy at this stage was a delicate affair, but as soon as his wife died and the Grand Duke married Bianca, Venice promptly proclaimed her ‘the adopted and beloved daughter of our Republic’. But the Republic fell discreetly silent when Francesco and Bianca suddenly died—ironically, for the Grand Duke’s hobby was alchemy, and the rumors said he spent his time brewing poisons from the crates of snakes and scorpions his agents sent from around the Mediterranean.

For centuries, historians tried to pin the murders on Francesco's brother and successor Fernando. Even after recent testing, scientists still enjoy arguing over the case. Some say the two were in fact victims of malaria; others swear it was arsenic.