Simone Martini 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 of Simone's life survives, and many attributions are debated by art historians. According to E. H. Gombrich, he was a friend of Petrarch and had painted a portrait of Laura.