Simon Cowell
In the words of the man himself, to leave Simon Cowell off this list would be equivalent to "biting into a doughnut without jam in the center." The British music executive in high-waisted trousers first snarked his way into U.S. living rooms in June 2001, when he appeared as a judge on the first season of the singing competition American Idol, a spin-off of the British show Pop Idol. With a reputation for making blunt remarks, insults and wisecracks, Cowell had a lot to do with the Fox show's skyrocketing ratings. American Idol has since been described as the most impactful show in the history of television, with Simon and fellow judges Paula Abdul and Randy Jackson helping to launch the careers of Kelly Clarkson, Carrie Underwood, David Cook and Kris Allen. The show's 10th season, which premiers on Wednesday, Jan. 19, 2011, will introduce two new judges, Jennifer Lopez and Steven Tyler, to replace the exiting Cowell. But America hasn't seen the last of him. In September, he's set to launch the U.S. version of another British singing contest, X-Factor — this time with groups and individuals over age 28 joining in.