Mr. and Mrs. Winfield
The Winfields are an elderly couple who live next door to the Simpson family early in the series and often talk about how crude and uncivilized the family is. They first appear in the season one episode "Homer's Odyssey", cracking jokes about Homer. The couple eventually move to Florida in the season four episode "New Kid on the Block" and have not been seen since (though it's implied that they died of old age, as Homer guessed that the Winfields are going to move to Florida to "run out the clock").
The couple appear in the season two episodes "Simpson and Delilah" and "Bart's Dog Gets an F", in which the wife is revealed to be named Sylvia. She also has a small speaking role in the Season 3 episode Separate Vocations when she mistakenly thinks Bart is being arrested by the Springfield police. The couple appear in the pre-2009 opening credits of The Simpsons, during the segment where Marge and Maggie pass many characters while driving home. Matt Groening named the Winfields after friends of his.
Read more about this topic: List Of Recurring The Simpsons Characters