Bad Guys with Depth

I've been writing about how to make any piece more literary.  Serious consideration ought to be given to the source of conflict, the antagonist, the monster, the bad guy, whatever it may be.  In nearly every piece, giving consideration to one's antagonist is just as important as to the protagonist.  I've read books and seen movies in which the antagonist is shallow, evil without subtlety, an easy straw man, or some other character  that is a one-dimensional character.  These are the stereotypical villains who are obviously evil.  These obvious villains undercut and trivialize your protagonist.  If your hero doesn't have a worthy and intriguing enemy, your hero, too, starts to fall flat. 

To figure out how to make a worthy enemy, carefully observe examples of such enemies.  Magneto from the X-men series is not literary, yet he exemplifies the villain who is more than just a man in black with a mustache and a maniacal laugh.  He sees himself as a hero, as someone worthy of emulation.  He sees the human race as the obstacle to world peace and, therefore, wants to eradicate it.  In his mind, he's the good guy.  He's flawed, but then, so are the heroes.  He's like Captain Nemo in Jules Vernes's novels, who seeks vengeance for what he deems justifiable reasons.  Such antagonists are not simply evil. 

In stories like Gregory Maguire's Wicked, the supposed villain actually becomes the protagonist.  As we get to know the witch Elphaba more, we see she never set out to be any kind of a villain but was portrayed as such by her society.  She was forced into the role of the villain, a role she never sought.  The Wizard, then, becomes the antagonist, and he doesn't view himself as a villain either but as someone doing good for society who is willing to destroy anything that stands in the way of his quest. 

The antagonist doesn't even have to be human or even humanoid to be complicated.  Moby Dick from the self-titled work is the antagonist of that piece.  He's a whale fighting for survival.  He's not a villain at all.  Captain Ahab can be seen as a villain, but he's on the side of the protagonist.  That work stands the test of time simply because it's not about simple bad guys and good guys. 

What makes the conflict in your piece work?  Who or what is the antagonist?  What is his/her/its motivation?  What makes your antagonist more than just a simple, shallow villain?  Spend as much time considering this character as you do the hero.  Are they foils, meaning opposites who have much in common?  If they are both equally complex, how does your villain highlight traits in your hero?