Kasem's voice was the key to his career. In 1964 during the Beatlemania craze, Kasem had a minor hit single called "Letter from Elaina", a spoken-word recording that told the story of a girl who met George Harrison after a San Francisco Beatles concert. At the end of the 1960s, he began working as a voice actor. In 1969, he started one of his most famous roles, the voice of Shaggy on "Scooby-Doo, Where Are You!". He also voiced the drummer Groove from "The Cattanooga Cats" that year.