Because you like Drusilla in Buffy the Vampire Slayer
Helena is a mentally unstable, childish, and completely merciless. And most of all, she's an unstoppable killer. See them in Orphan Black.
Mike Hannigan is a lawyer-turned-pianist who loves to tap into his kooky side. See them in Friends.
Kilgrave is a domineering, abusive boyfriend. Then, add in the power of mind control. See them in Marvel Cinematic Universe.
Catwoman might be slightly unhinged, but you can't say this feline villainess isn't confident. See them in DC Extended Universe.
Kathryn Merteuil may be a vain sociopath, but you won't be able to look away. See them in Cruel Intentions.
Christine Daae has been secretely taking lessons from a phantom musician. It sounded less creepy in her head. See them in The Phantom of the Opera.
Nadia Vulvokov is a no-nonsense broad with a dark sense of humor and a flippant attitude. See them in Russian Doll.
Sabrina Fairchild is irresistible. See them in Sabrina.
Luke Danes will serve you coffee and always be there for you to help out. See them in Gilmore Girls.
Give in to the dark side with vampire Lestat; it's more fun. See them in Interview with the Vampire: The Vampire Chronicles.
Andy Bernard is a preppy Cornell grad who's very likely to break into an acapella performance. See them in The Office.
Dorothy Gale is a down-home Kansas girl in a bizarre fantasy land with beautiful red shoes. See them in The Wizard of Oz.