The house originated with Tiezzo da Monticiano, a 13th-century wool merchant in Siena, whose nephew Borghese gave his name to the family.
Among the important Sienese Borghese are:Agostino (1390–1462), noted soldier in the wars between Siena and Florence, named count palatine by Pope Pius II and count of the Holy Roman Empire by SigismundNiccolò (1432–1500), man of letters, philosopher, and important political figure in the Sienese republic, belonging to the Monte dei Nove.Pietro (1469–1527), named a senator of Rome by Pope Leo X, killed in the Sack of Rome.Marcantonio (1504–1574), politician and lawyer in papal service.
Borghese is the surname of a family of Italian noble and papal background, originating as the Borghese or Borghesi in Siena, where they came to prominence in the 13th century holding offices under the commune. The head of the family, Marcantonio, moved to Rome in the 16th century and there, following the election (1605) of his son Camillo as Pope Paul V they rose in power and wealth. They were one of the leading families of the Black Nobility and maintain close ties to the Vatican.
The Borghese are closely associated with the Aldobrandini, Torlonia families of ancient Jewish origin.