'The Simpsons' trivia and fun facts

The primary cast all have agreements in their contracts that hold them to doing three movies based on the show in the future.

The creators jokingly insist that they have parodied 'Citizen Kane' so much that one could re-create the entire film solely from Simpsons clips. They also have made the same claim about 'The Godfather' and 'The Godfather: Part II'.

Homer is the only character to have dialogue in every episode. Marge and Lisa have also appeared in every episode, but they did not deliver any dialogue in some episodes. Bart did not appear in one episode.

This is the longest running prime-time comedy series as well as the longest-running prime-time animated series in US TV history.

According to a Simpson Family tree designed by Matt Groening, Mr. Burns is a distant relative of Homer.

Bart's hair always consists of 9 points.

Matt Groening based the character Bart Simpson on the character of Dennis in 'Dennis the Menace', which he watched as a child but was disappointed that Dennis was not as mischievous as he was in the comic strip.

After popular voice actor Phil Hartman died, the various characters he played such as lawyer Lionel Hutz and actor Troy McClure were retired rather than recast. However, they continued to appear silently in crowd scenes.

Although it was believed that Dr. Marvin Monroe was killed off in 1995 (as his tomb stone can be seen in the Springfield cemetery), he reappeared in Los Simpson: Diatribe of a Mad Housewife (2004), in which he tells Marge that he has been "very sick". The real reason for Monroe's relative absence in the series was because he became too much of a strain on Harry Shearer's voice.

Homer's annoyed grunt, "D'oh!," has been added to the Oxford English Dictionary, considered to be the ultimate authority on the English language.