Sebastiano Folli (1568–1621) was an Italian painter of the late Renaissance period. He was a scholar of Alessandro Casolano, and a native of Siena. He distinguished himself by several frescoes in the churches at Siena, particularly the cupola of Santa Marta, and some subjects from the Life of St. Sebastian, in the church of that saint, painted in competition with Rutilio Manetti, to whose pictures they are in no way inferior. He visited Rome, and was employed in some considerable works for the Cardinal de' Medici, afterwards Leo XI. He died in 1621.