Giovanni Francesco Barbieri (otherwise called Guercino, from his squinting), (1591-1666), Italian historical painter, was born at Cento, a village not far from Bologna. His artistic powers were developed very rapidly, and at the age of seventeen he was associated with Benedetto Gennari (1550-1610), a well-known painter of the Bolognese school. The fame of the young painter spread beyond his native village, and in 1615 he removed to Bologna, where his paintings were much admired. His first style was formed after that of the Caracci; but the strong colouring and shadows employed by Caravaggio made a deep impression on his mind, and for a considerable period his productions showed evident traces of that painter's influence. Some of his latest pieces approach rather to the manner of his great contemporary Guido, and are painted with more lightness and clearness. Guercino was esteemed very highly in his lifetime, not only by the nobles and princes of Italy, but by his brother artists, who placed him in the first rank of painters.

He was remarkable for the extreme rapidity of his execution; he completed no fewer than 106 large altar-pieces for churches, and his other paintings amount to about 144. His most famous piece is thought to be the St Petronilla, which was painted at Rome for Gregory XV. and is now in the Capitol. In 1626 he began his frescoes in the Duomo at Piacenza. Guercino continued to paint and teach up to the time of his death in 1666. He had amassed a handsome fortune by his labours. His life, by J. A. Calvi, appeared at Bologna in 1808.

His brother, Paolo Antonio Barbieri (1603-1649), was a celebrated painter of still life and animals. He chose for his subjects fruits, flowers, insects and animals, which he painted after nature with a lively tint of colour, great tenderness of pencil, and a strong character of truth and life.