3. Waylon Smithers
As Mr. Burns' sniveling foil, Waylon Smithers – or, most often, referred to as simply "Smithers!!" with some extra disgust and exclamation points thrown in – seems like the diametric opposite to the great and powerful nuclear-plant owner. The executive assistant speaks in a nasal, mostly monotonous voice that only changes in volume and (slightly) in pitch, depending on how annoyed he is (usually with Homer). Since Shearer voices both Smithers and Mr. Burns, it's fun to imagine how often his expression changes when assuming each role when they're in the same scene.