Because you like Ultron in Marvel Cinematic Universe
His superiority complex coupled with his bitter desire for revenge makes Vegeta a formidable foe. See them in Dragon Ball Z.
Light Yagami has a plan to make a better world, and morals won't stop him. See them in Death Note.
Don't worry about this forensic scientist offing you unless you're a serial killer yourself. (You're not, right? Just checking.) See them in Dexter.
Lelouch vi Britannia is a high school student by day, masked destroyer of tyrannical empires by night. See them in Code Geass.
Severus Snape is a misanthropic potions teacher with a vindictive streak. See them in Harry Potter Series.
Nick Miller might not have a bank account, but he defintely has a lot of love to give. See them in New Girl.
Aragorn is the one true king, a title he is too humble to accept. See them in The Lord of the Rings.
After years of being a nerdy loner, Seth Cohen can't wait to shower charm on his newfound friends. See them in The O.C..
An underdog with nothing left to lose, Donnie Creed has everything to prove. See them in Creed.
Guillermo is the best servant a vampire could ask for. For years now. Not that he's counting. See them in What We Do In The Shadows.
A hurricane of a human being, Marla Singer is destructive and unforgettable. See them in Fight Club.