Baldassare Tommaso Peruzzi (7 March 1481 – 6 January 1536) was an Italian architect and painter, born in a small town near Siena (in Ancaiano, frazione of Sovicille) and died in Rome. He worked for many years with Bramante, Raphael, and later Sangallo during the erection of the new St. Peter's. He returned to his native Siena after the Sack of Rome (1527) where he was employed as architect to the Republic. For the Sienese he built new fortifications for the city and designed (though did not build) a remarkable dam on the Bruna River near Giuncarico. He seems to have moved back to Rome permanently by 1535. He died there the following year and was buried in the Rotunda of the Pantheon, near Raphael.
He was a painter of frescoes in the Cappella San Giovanni (Chapel of St John the Baptist) in the Duomo of Siena.