As the man behind Count von Count, puppeteer Jerry Nelson helped teach generations of kids how to count. The performer died on Thursday at age 78 of unspecified causes, according to CBC Radio-Canada.

Nelson created the number-loving Count von Count on Sesame Street -- not to mention Mr. Snuffleupagus and Grover's customer Mr. Johnson. He also played Gobo Fraggle, the central character on HBO's Fraggle Rock.

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Born in Tulsa, OK and raised in Washington, DC, Nelson began working with Muppets creator Jim Henson in 1965, and performed full-time on Sesame Street beginning in the 1970s. Working on The Muppet Show plus the films The Muppet Movie and The Great Muppet Caper, he played such characters as Sgt. Floyd Pepper (of the band Electric Mayhem), Pigs in Space's Dr. Julius Strangepork, Kermit the Frog's nephew Robin and Gonzo's chicken girlfriend Camilla.

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Although health reasons forced him to retire from operating Muppets characters in 2004, he continued to voice the Count until his death.

This article originally appeared on Jerry Nelson, Voice of Sesame Street's Count, Dead at 78