The actor voiced Stu Pickles on 'Rugrats.'
Jack Riley, famous for his roles on The Bob Newhart Show and Rugrats, died of pneumonia in Los Angeles on Friday, a source close to the family confirms to ET. He was 80.
Riley is perhaps best known for his role as the neurotic Elliot Carlin, one of Bob Newhart's patients on The Bob Newhart Show, appearing in nearly 50 episodes of the series.
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The Cleveland native made his rounds on television during the '60s and '70s, appearing on iconic shows such as I Dream of Jeannie, The Partridge Family, M*A*S*H, Mary Tyler Moore, Happy Days, and Police Woman, before making his transition to film. Riley starred in several movies throughout the late '70s and '80s, such as High Anxiety in 1978, History of the World, Part I in 1981 and Spaceballs in 1987.
While Riley worked steadily throughout the following decades, it was his voice role as Stu Pickles on Rugrats and its follow-up series, All Growed Up!, that brought him fame with the younger generation.
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Many of Riley's admirers have taken to Twitter to mourn the actor, including his Rugrats co-star Julia Kato.
"RIP Jack," Kato wrote on Twitter. "You were a kind soul, classy & so talented to work with on #Rugrats. Prayers to his family."
Riley is survived by his wife, Ginger Lawrence.