In "Amadeus," Antonio Saleri is portrayed as classical composer of mediocre ability who was eaten up by his envy of Mozart. He is portrayed as sick, miserable, jealous ... but is this true? I am not a musical scholar, but as a musician I was always interested in how real this portrayal is. Since I have not learned enough, I won't take an absolute position, but I am going to give you some resources that will help you get started.
If asked for my slightly informed opinion, I think the director of "Amadeus" took a real historical person and altered his character for his own purposes.
It has also been rumored that Salieri poisoned Mozart, accounting for his "sudden" death. I've included a final link that discusses this possibility. It's a little long and dry, but it is interesting.
Check the sources below and see what you think.