Pietro Lorenzetti (or Pietro Laurati; c. 1280 - 1348) was an Italian painter, active between approximately 1306 and 1345.
He was born and died in Siena. He was influenced by Giovanni Pisano and Giotto, and worked alongside Simone Martini at Assisi. He and his brother, Ambrogio Lorenzetti, helped introduce naturalism into Sienese art. In their artistry work and experiments with three-dimensional and spatial arrangements, they foreshadowed the art of the Renaissance.
Many of his religious works are in churches in Siena, Arezzo, and Assisi. One of his last works is the Nativity of the Virgin (1342), now in the Museo dell'Opera del Duomo. His masterwork is a tempera fresco decoration of the lower church of Basilica of San Francesco d'Assisi, where he painted a series of large panels depicting Crucifixion, Deposition from the Cross, and Entombment with figures displaying emotions, yet the massed figures in these scenes are governed by geometric emotional interactions, unlike many prior scenographic depictions which appeared to be the independent iconic agglomerations, as if independent figures had been glued on to a surface, with no compelling relationship to one another. The narrative influence of Giotto's frescoes in the Bardi and Peruzzi Chapels in Santa Croce (Florence) and the Arena Chapel (Padua) can be seen in these and other works of the lower church. The Lorenzetti brothers and their contemporary competitor from Florence, Giotto, but also his followers Bernardo Daddi and Maso Di Banco, seeded the Italian pictorial revolution that extracted figures from the gilded ether of Byzantine iconography into pictorial worlds of towns, land, and air. Sienese iconography was generally more mystical and fantastic than the more naturalistic Florentines, and at times, seems to elevate into what appears a modern surrealist landscape.