Because you like Allie Hamilton in The Notebook
A monstrous pirate captain, Davy Jones is quite literally heartless. See them in Pirates of the Caribbean: the Curse of the Black Pearl.
Aerith Gainsborough has lived a simple life, but when the world is threatened she's willing to step up and do whatever she can to help. See them in Final Fantasy Series.
When Andrew Neiman is not in classes during the day, he's rehearsing his drums until his hands bleed at night. See them in Whiplash.
Miss Havisham is the creepiest old rich lady in town. See them in Great Expectations.
Kat Stratford is part of the "out" crowd and proud of it. See them in 10 Things I Hate About You.
After becoming accepted into the group of popular girls, Tracy Freeland has turned from a sweet and reserved teenager into a monster. See them in thirteen.
Spencer Reid's super-smarts helps catch killers, and his social awkwardness endears co-workers. See them in Criminal Minds.
Ultron is security software turned evil mastermind. See them in Marvel Cinematic Universe.
It's easy to see why Poe Dameron would side with the rebellion: he's bad at taking orders, likes to show off, and is committed to the cause. See them in Star Wars Series.
A malevolent dark wizard, Voldemort is so fearsome that he's known primarily as "He Who Must Not Be Named." See them in Harry Potter Series.