Prospero da Siena (unknown - 1500) was a high ranking Borgia guard in Rome and Captain of one of the three Borgia towers that ruled over the Antico District.


In 1500, Ezio Auditore da Firenze, during his quest to liberate Rome from the Borgia rule, killed Prospero and burned down the tower in which he resided. Subsequently, the surrounding region was freed from Borgia oppression.

Two of Prospero's brothers, Pietro and Valentino, were also captains employed by the Borgia family.