Caravaggio
Huge new churches and palazzi were being built in Rome the last years of the 1500s and the first years of the 1600s.  These big churches needed paintings to hang on the walls. The Counter-Reformation Catholic Church wanted to find painters who would paint beautiful art about God.  They wanted people to like the art so much that they would think Protestantism was ugly and boring, and wouldn't want to start being part of a Protestant church. So the Catholic Church needed a new type of art, because Mannerism had been the most famous type of art for 100 years, and now it was boring.  Caravaggio's paintings were new, and different from Mannerism.  He painted in a way called naturalism, which means that he painted things how they actually looked. He painted pictures of people so that the people looked real, and he made his pictures look exciting by painting a lot of very dark shadows and very bright lights (which is called chiaroscuro).