Michelangelo Merisi da Caravaggio was a great talent but not so great a person. I early quote about him says “after a fortnight’s work he will swagger about for a month or two with a sword at his side and a servant following him, from one ball-court to the next, ever ready to engage in a fight or an argument, so that it is most awkward to get along with him.”. And of course famously he ended up killing some one later. But there can be no argument about his talent.
As a side note this does bring up a question about how the artist affects his work. But I will save that for another post:)
You can see more of his work and a short biography at http://www.caravaggio-foundation.org