John Swartzwelder is an American writer, best known for his work on the animated television series The Simpsons, as well as a number of novels. He is credited with writing the largest number of The Simpsons episodes (55 full episodes, with contributions to four others) by a large margin. Swartzwelder was one of several writers recruited to The Simpsons from the pages of George Meyer's Army Man magazine.

Has written almost a sixth of all "Simpsons, The" (1989) episodes.

Famous for being reclusive, he has steadfastly refused to participate in any commentary for the Simpsons DVDs.