Taddeo di Bartolo (c. 1363 – 26 August 1422), also known as Taddeo Bartoli, was an Italian painter of the Sienese School during the early Renaissance. He is among the artists profiled in Vasari's biographies of artists or Vite. Vasari claims he is the uncle of Domenico di Bartolo.
Much of his early work was in Pisa, where he was responsible for the frescoes of Paradise and Hell in the Cathedral there, and for paintings in the Palazzo Pubblico and the church of San Francesco.
At the Collegiata di San Gimignano, Taddeo painted a fresco depicting The Last Judgment. The Museo Civico of San Gimignano, displays a painting by Taddeo depicting Saint Gimignano holding the town in his lap (c. 1391).
A triptych of the Virgin and Child with St John the Baptist and St Andrew, painted around 1395, is on display at the Szépművészeti Museum of Fine Arts in Budapest. A massive triptych, Assumption of the Virgin, painted in 1401, is displayed in the 16th-century Duomo of Santa Maria dell'Assunta at Montepulciano.
Taddeo's Madonna with Child, Four Angels and Saint John the Baptist and Saint Andrew may be seen in the Oratory of the Company of Saint Catherine of the Night at Santa Maria della Scala, Siena. He also painted allegories and figures from Roman history (1413–14), and the Funeral of the Virgin (1409) at the Palazzo Pubblico in Siena.
A Madonna and Child (c. 1400), painted with tempera and oil on a panel, is located in the Wadsworth Atheneum. Two more Madonna and Child paintings are in the collection of the Museum of Fine Arts, San Francisco, California, and the Musée du Petit Palais, Avignon, France. Another "Madonna and Child" is displayed at Ball State University's Museum of Art in Muncie, Indiana. Taddeo painted a Saint Germinianus displayed at the Snite Museum of Art in Notre Dame, Indiana. He painted an Annunciation now displayed at the Bergen Art Museum in Bergen, Norway. The Australian Catholic University has an Annunciation (1401) in its Melbourne campus chapel  Taddeo painted a Christ Meeting Mother on Way to Calvary on display in the Worcester Art Museum in Massachusetts. Taddeo painted a Madonna and Child With Angels on display in the Fogg Art Museum in Cambridge, Massachusetts. Taddeo painted a Madonna and Child and Sanits was on display in Palazzo Blu, Pisa.