Macbeth is a hero gone bad. In the first Act of the play, the viewer is told of how mighty and awesome Macbeth was as he performed in battle. King Duncan wants to reward that bravery and makes him Thane of Cawdor. Macbeth has a very active conscience, and doesn't always desire to kill Duncan. In fact, he even tells Lady Macbeth that he won't go through with it. All this serves as evidence that he is a good guy. A hero.
But no hero is without fault. Macbeth is no different. He's power hunger, but not nearly to the extent of Lady Macbeth. Probably his biggest fault is his ambition. I have a really hard time calling that a fault, though. There is nothing wrong with ambition in and of itself. Plenty of readers believe that Macbeth's ambition was pushed over the edge by Lady Macbeth's prodding. I can see that, and I think it was a part of it, but I don't think that excuses Macbeth.
He's a hero turned bad because at the end of the day, Macbeth killed Duncan. And then he continued to kill and have people killed to cover up his murder and keep his position on the throne. As Lady Macbeth was consumed with more and more guilt, Macbeth simply kept on killing. I just can't support the idea that Macbeth is "a victim of evil." I can't support it because inherent with the word "victim" is the idea that the events occurred outside of his control; everything happened to him without his input. He's not a victim. He played an active role in his downfall.