Julian Assange will pop up on The Simpsons this Sunday, landing the embattled WikiLeaks leader in the historic 500th episode of an animated show known for its quirky cameos.

"We specialize in finding people who can't be found, so we thought it would be unique for the 500th episode," said The Simpsons producer Al Jean in a conference call with reporters. "We had to record him over the phone. It was a cloak-and-dagger kind of thing."

Assange's unlikely cameo is just the latest celebrity "get" for the show's bookers, who have long specialized in lining up surprising special guests. (See the cameos we've selected as our favorite Simpsons guest stars from the first 500 episodes in the video gallery above.)

How did the controversial cartoon land the controversial WikiLeaks chief? Jean said he found out from Simpsons ' creator Matt Groening that Assange, whose lines were recorded months before Sunday night's benchmark episode, wanted to be on the show. The task of coordinating the cameo was left to intrepid casting director Bonita Pietila, who previously located mysterious cultural heroes like Banksy and Thomas Pynchon.