"The Principal and the Pauper" is the second episode of The Simpsons ' ninth season. It originally aired on the Fox network in the United States on September 28, 1997. In the episode, Seymour Skinner begins to celebrate his twentieth anniversary as principal of Springfield Elementary School when a man arrives claiming that Skinner has assumed his identity. Principal Skinner admits that his name is actually Armin Tamzarian. He had thought that the real Skinner, a friend from the army, had died in the Vietnam War. Tamzarian decides to leave Springfield forever, only to return later in the episode. The episode was the last written by Ken Keeler and was directed by Steven Dean Moore. It guest starred Martin Sheen as the real Seymour Skinner. Although it was produced by Bill Oakley and Josh Weinstein as part of the season eight production code, it aired during the ninth season as a holdover. The title of the episode is a reference to the book The Prince and the Pauper by Mark Twain.

"The Principal and the Pauper" has become one of the most controversial episodes of The Simpsons. Many fans and critics reacted negatively to the fact that Principal Skinner, who had been a recurring character since the first season, was suddenly revealed to be an imposter. The episode received criticism from series creator Matt Groening and Harry Shearer, the voice actor of Principal Skinner. Despite this, Ken Keeler considers the episode to be the best work he has ever done for television. The episode received generally negative reviews in several articles and books on The Simpsons.