Duke or Duchess San Donato (Italian: Duca o Duchessa di San Donato) was a noble title, first created in 1602 by the Spanish King Philip III for the Sanseverino family. The duchy was traditionally based on estates and territories held in San Donato di Ninea, Calabria. The first creation, however, lasted only 52 years. In 1668, the title was recreated for a wealthy merchant, Antonio Amitrano, who had some years earlier bought the feudal rights over the former dukes' territories. Descendants of the Ametrano family held the duchy, as one several titles, until it became extinct in the 1970s. There have been successive claims over the centuries by distant kinsmen of the first holders to claim the duchy; these remain unverified.
The history of the Duchy of San Donato can be traced to 1374, when following the wedding of Margherita di Sangineto with Venceslao di Sanseverino, Count of Tricarico and Chiaromonte, as part of the bride's dowry, feudal and territorial rights over lands in the area of San Donato di Ninea, passed to Sanseverino family. The family continued to hold the estates until in 1510, when Bernardino Sanseverino, Prince of Bisignano, granted them to a distant relation, Francisco Sanseverino, Baron of Càlvera. This began the lineage of the Sanseverino barons, later to be the first dukes of San Donato. The Sanseverino name was to remain linked, albeit tentatively, with the duchy throughout its history. At the height of its glory throughout Genoa, Venice, Milan, Piacenza, Modena, Capua, Salerno and Naples the family held ten princely titles, twelve duchies, nine marquessates and forty members of the family held the title count.
In 1598, the Baron of Càlvera were elevated, by the governing Spanish authorities, to the rank of Marquess of San Donato. This was to be a stepping stone to greater titles, for on 29 September 1602, Philip III of Spain created Scipione, 3rd Baron of Càlvera and 4th Baron of Policastrello, Duke of San Donato. Thus, establishing the duchy. This was a common ploy by the Spanish, for keeping the powerful nobility of the occupied country loyal to Spain, rather than as a reward for any great service on the part of the newly created duke.
Three years after the creation of the duchy, greater good fortune was to come to the new duke. In 1605, his mother, Lucrezia Carafa, inherited the estates of Roggiano from the Prince of Bisignano. From this time, the ducal court was now resident for much of the year at Roggiano, rather than San Donato. Scipione, Duke of San Donato died in 1640 and was succeeded to the title by his son, Francesco.