Biography:

Jerry Nelson (July 10, 1934 – August 23, 2012) was an American puppeteer, best known for his work with The Muppets. Renowned for his wide range of characters and singing abilities, he performed Muppet characters on Sesame Street, The Muppet Show, Fraggle Rock, and various Muppet movies and specials. Description above from the Wikipedia article Jerry Nelson, licensed under CC-BY-SA, full list of contributors on Wikipedia.