Michelangelo Merisi da Caravaggio (1571-1610) may have been art’s first “bad boy.” A difficult and troubled personality, he was constantly at odds with the world. Born in Milan, he moved to Rome to further his career. He was arrested a number of times for violent conduct and finally killed a man in a fight. He was forced to leave Rome, Naples, Malta, and Sicily successively because of trouble with the law. (Portrait by Ottavio Leoni)
But he was one of history’s greatest and most influential artists. He adopted and refined the technique of chiarascuro painting--contrasts of light and dark--and his use of the technique later influenced Rubens and Rembrandt, among others. Many of his paintings hang in Roman churches and chapels.
David with the Head of Goliath (Goliath's head is a self-portrait)
Caravaggio was controversial in his time for more than his behavior. Many of his paintings were rejected, especially by churches, because of his insistence on portraying Christ and his disciples as poor peasants. He even had a prostitute pose for a painting of the Virgin Mary.
The Conversion of St. Paul on the Road to Damascus may be his masterpiece, one of his most powerful works. It depicts the moment when Saul of Tarsus, a persecutor of early Christians, heard the voice of Christ and fell to the ground in ecstasy; he became the apostle St. Paul, who was instrumental in spreading Christianity throughout the Mediterranean world. Notice how the light falls on Paul, yet the center of the painting is dominated by his horse. The light and the horse's raised leg draw the viewer's eye down almost to be surprised by the figure lying on the ground.
See here for a collection of all of Caravaggio's works.