America's most famous dysfunctional cartoon family have played out their lives before a worldwide audience for more than two decades since the characters Homer, Maggie and children Bart, Lisa and baby Maggie first burst onto the small screen in 1989.

Now in its 23rd season, the series has become the longest-running comedy in US television history, as well as the longest-running prime-time scripted show.

In the 500th show, Homer and Marge discover Springfield residents are holding a secret meeting to kick them out of town for all the trouble they've caused over the years.

After being sent into exile, the Simpsons arrange to meet with Assange in a bid to clear their names.

The show's executive producer Al Jean acknowledged earlier that Assange, who leaked massive amounts of sensitive diplomatic and military documents, is a controversial figure.

"There was discussion internally whether or not to have him on the show, but ultimately we went ahead and did it," Jean told Entertainment Weekly magazine, adding: "There's nothing we did that has anything to do with the legal situation that he's in."

Assange is wanted in Sweden in connection with allegations of rape and sexual assault, and he fears extradition to the United States for possible prosecution for the leaks.

"Thanks for 500 shows," the show said in a note attached to the end of Sunday's milestone episode.

The Simpsons have a history of including high- profile guest appearances, from Hollywood stars and musicians to politicians.

AGENCE FRANCE-PRESSE