Because you like Richard Harrow in Boardwalk Empire

His murderous megalomania aside, Loki is quite charming. Just don't mention his strapping older brother; he's a tad jealous. See them in Marvel Cinematic Universe.

Severus Snape is a misanthropic potions teacher with a vindictive streak. See them in Harry Potter Series.

A wildly brilliant detective, Sherlock Holmes can figure out everything except how to interact with other human beings. See them in Sherlock.

Both intelligent and empathetic, Remus Lupin is worn down by the weight of a secret. See them in Harry Potter Series.

A bookish know-it-all with a bossy streak, Hermione Granger always stands up for what she believes in. See them in Harry Potter Series.