Seth MacFarlane on Simpsons FinaleHe produces and voices a good chunk of Fox’s Sunday animation block but Seth MacFarlane has never been on The Simpsons until now. The multitasking MacFarlane will make his debut on TV longest running scripted series’ season finale on May 19. He will guest voice as “Ben,” a married man who Marge gets to know online on a swingers site. Lisa Lampanelli is also guest voicing on The Simpsons’ one-hour Season 24 ender. Oscar host and The Family Guy, American Dad and The Cleveland Show creator, EP and voice actor MacFarlane joins a long long line of exalted Simpsons guest stars including Thomas Pynchon, Johnny Cash, Tom Waits, Buzz Aldrin, John Waters and News Corp boss himself Rupert Murdoch, who appeared in Season 10.