Born July 10, 1934, in Tulsa, Okla., Nelson grew up in Washington, D.C., where he first met Jim Henson. The two began a long and fruitful creative collaboration when Nelson became a regular on "Sesame Street" during the landmark show's second season in 1970. Though best known for his portrayal of Count von Count (whose personality was inspired by Béla Lugosi's Count Dracula), Nelson also performed Herry Monster, Sherman Hemlock, Sgt. Floyd Pepper and Kermit the Frog's nephew, Robin.
In addition to his Muppets alter-egos, Nelson performed Gobo and Marjory the Trash Heap on "Fraggle Rock" (1983-87), while his films include voice work in The Dark Crystal (1982), The Christmas Toy (1986) and The Muppets (2011). Nelson died Aug. 23, 2012.