Over the past 24 years, there's been a veritable ton of celebrity guest stars appearing on The Simpsons, all too eager to send themselves up in order to extend their fame across the show's enormous fanbase. There have been some amazingly memorable celebrity appearances on The Simpsons: who could forget Sting digging Bart out of the well in 'Radio Bart' (despite Bart never having played one of his albums), or The Smashing Pumpkins raiding Peter Frampton's cooler at Hullabalooza? There have been plenty of times where celebrities have appeared as themselves throughout the show's history, but what about those who have played characters in the show? Kelsey Grammar returning time and again to voice Bart's nemesis, Sideshow Bob (with sublime results,) is a prime example, and easily one of the best known. But there have been some that are slightly lesser known and definitely less noticed. Take a look at the top 12 celebrity voiceovers in The Simpsons you may never have recognised first time round...
