I hesitate to mention this because it's such a terrible, TERRIBLE ending to an otherwise good film, but... the robots at the end of Spielberg's "AI" movie, that rescue the lead character/robot. They seemed well-intentioned and "good" to me.

Another example of a race of good robots, although it's a "tough love" variety.... is "Gort" from The Day the Earth Stood Still. Klaatu says he represents a group of independent, galactic police robots that keep peace in the galaxy.

There are plenty of examples of robots working alongside humans (or other aliens) as happy servants, but you're right that when they're presented as an *independent* society, they're almost always evil. I had a hard time coming up with just those two examples... and Gort is maybe a stretch, depending on how you feel about civil liberties and robots standing over you with a big stick.

Science fiction, classically, is often a warning about technological hubris. What better way to convey "don't become too dependent on technology" than to have that technology attain sentience and try to wipe out humanity?

How do you recognize an evil being? Does it have a pink skin and only two legs? It is definitely evil and should be wiped out from the galaxy!

But seriously. There is no valid definition of what is "evil". What I can call "evil" can someone call "good". I remember one contemplation of one Czech SF author. There is a term "evil weapon" in SF quite often. He was thinking about how stupid this term is. Let us say the evil weapon is a nuke. With the nuke you can kill huge amount of innocent people. You can imagine the nuke in the hand of some terrorist band.

But how about other weapons? E.g. a gun. A terrorist with a gun is not able to kill as many innocent people as with the nuke. At least not so quickly. But the terrorist can kill a lot of people with it too. So this gun is not so evil as a nuke, but it is evil. Hey! Wait a minute! The terrorist can kill ME with that gun! Who cares about the other people? He can shoot me! The gun is as evil as the nuke.

But what if I take this particular gun and kill that bloodthirsty terrorist? It may save a lot of people. It would the be good thing. No doubt. But makes this the gun to be more good? I guess not. It is the matter of who holds the trigger.

Probably "is it evil" is not right question. The right question might be "Will it that harm me?" If so, I would say it is evil. If not it is good. The robot that makes shoes for me is good. No doubt. The robot that makes shoes for my neighbor is good too. The robot that makes shoes for me and kills my neighbor is good too. I like my shoes and don't like my neighbor. Well I might say the robot is good, but my neighbor will never agree with me under such condition. You see evil and good is only thing of the point of view.