"Good" vs. "Evil"

While reading Shakspeare's "Romeo and Juliet," I noticed mention of good versus evil. As in many books, there are good charactors, and evil charactors. Although no one in the play is neccesarily either, I couldn't help but notice the theme of good vs. evil.
Is there a good? Is there an evil?
There is the classic good: Heroic saviors, only thinking of others and doing the right things and never losing.
And there is the classic bad: Dark, mysterious people who want to control the world but somehow always end up losing, even when success is close.
Buddhism and peace also came to my mind. If so many people (but still, too few) believe that there is good in everyone, why isn't there? Well, maybe there is! It just depends on your point of veiw. This is where it came to me.
Good and evil all depend on your position on the matter.
So lets say there is someone who is killing a bunch of people with red hair because he doesn't like the color red (this is an example, it never happened, just trying to explain this in a way that doesn't insult anyone [I am also a red head]). Now, in your opinion, you might think this person is "evil." He is doing a bad deed to innocent carrot-tops.
BUT in his mind, he is "good." He is ridding the world of disgusting red heads. He is doing a good deed.
So, he isn't evil, and he isn't good.
Another hypothetical example:
There is this woman who gives money to companies that would limit the ammount of gas-guzzling cars in the world. To the woman, she is "good" and is doing good deeds.
BUT to a gas-guzzling car sales person or enigineer, she is "bad" or maybe even "evil" because she is making this sales person or engineer get less money.
So who is "evil?" Who is "good?"

-PEACE