27. Donald Sanger, The Bubble Boy
Best-known episode: "The Bubble Boy"
Unlike John Travolta's affably goofy character in the 1976 TV movie The Boy in the Bubble, Seinfeld's Bubble Boy was just an asshole. Like that Travolta character, Donald Sanger is modeled after the real-life David Vetter, a boy whose immune system was so weak it required him to live his entire life in a sterilized plastic "bubble." We never actually see him, but Sanger (voiced by Jon Hayman, a writer and consultant for the show) has none of the sympathetic qualities usually attributed to kids who battle lifelong illness. He berates his devoted mother ("What the hell do I gotta do to get some food around here? And if it's peanut butter, shove it in your face!"), and when he meets Susan Ross, he suggests, "How about taking your top off?" It's actually kind of a relief when she accidentally deflates his bubble and he's rushed off to the hospital. JENNY ELISCU