4. Principal Seymour Skinner
Bart's perennially buttoned-up yet socially ill-equipped principal, Seymour Skinner (or "Armin Tamzarian," but who's asking?), has long served as the straight man to the mischievous preteen's antics. From the way he cowers around Superintendent Chalmers and his mother to rare moments of humanity — as when he was courting girlfriends like Mrs. Krabappel and Marge's sister, Patty — Skinner is about as nuanced as a Simpsons character can get. Shearer's portrayal homes in on Skinner's earnest unwitting-ness in a manner that makes you laugh at him and feel bad for him simultaneously; it's hard to imagine any other actor striking that same balance with the character.