Stevie Wonder (b. 1950) made a guest appearance on a 1973 episode of Sesame Street. He performed "123 Sesame Street" and his hit "Superstition," and talked to Grover. Many of the street scenes from that episode were repeated on the show as inserts.
He appeared in "Yakety Yak - Take It Back", a recycling PSA that eventually aired on Sesame Street.