The 15 Best Simpsons One-Off Characters Ranked

After 32 years on the air, it takes real mettle to appear in only one episode of "The Simpsons" and leave such an impression that the audience never forgets you. And yet, some characters make such a grand contribution to the series, or provoke such a change in one of our beloved regulars, that a single adventure is all we needed to see. In that spirit, we salute those magnificent one-timers who, even with their brief screen time, made an indelible mark on the greatest television show of all time. But first, a few honorable mentions! Hats off to Frank Grimes, Birch Barlow, Homer's college nerd buddies, and...