GLaDOS (Portal 1+2)

She was supposed to be the greatest, most efficient supercomputer and AI of her time, capable of managing the entirety of Aperture Laboratories’ underground facility, managing and reviewing thousands of test subjects. And that, she did, but much like the supercomputer EPICAC from Kurt Vonnegut’s short story of the same name, she did it seemingly hesitantly, and indeed, absolutely alone. Once she killed the entire human staff, that is.

I think GLaDOS is one of the greatest sci-fi characters because she is an absolutely conflicted being herself in a story reflecting its own conflict. Throughout the games she shames the main character for being a smelly, stupid human, with feelings and distracting emotions. But then you eventually notice something about her. She holds grudges, she hates, and she’s hesitant. Despite her hatred and logical destruction of humans, she is very emotional in her own way. I won’t spoil anything, but this also induces a change of her at the end of the story, furthering my point.

On top of this, she plays the roles of both the hero and villain between the two Portal games, reluctantly in the former.  Nonetheless, by the end you see GLaDOS change from a monotone testing apparatus with no regard for human life to a passionate, merciful friend of the protagonist.

GLaDOS: You look ugly in that jumpsuit. That's not my opinion; it's right here on your fact sheet. They said on everyone else it looked fine, but on you, it looked hideous. But still what does an old engineer know about fashion? Oh, wait, it's a she. Still, what does she know about - oh, wait. She has a medical degree. In fashion. From France. 

GLaDOS: You know, I'm not stupid. I realize you don't want to put me back in charge. You think I'll betray you. And on any other day, you'd be right. The scientists were always hanging cores on me to regulate my behavior. I've heard voices all my life. But now I hear the voice of a conscience, and it's terrifying... because for the first time it's *my* voice! I'm being serious. I think there's something really wrong with me!