Simone Martini (c. 1284–1344) was an Italian painter born in Siena. He was a major figure in the development of early Italian painting and greatly influenced the development of the International Gothic style.
It is thought that Martini was a pupil of Duccio di Buoninsegna, the leading Sienese painter of his time. According to late Renaissance art biographer Giorgio Vasari, Simone was instead a pupil of Giotto di Bondone, with whom he went to Rome to paint at the Old St. Peter's Basilica, Giotto also executing a mosaic there. Martini's brother-in-law was the artist Lippo Memmi. Very little documentation survives regarding Simone's life, and many attributions are debated by art historians.