ANSWER
The Andy Griffith Show.
Everyone remembers that little Ronnie Howard played "Opie", but in January 1962 Clint Howard appeared as "Leon". He was only two years old. He also appeared in an early episode of Star Trek (the original series). Interestingly, his character in Star Trek was bald, so he looked much like he does today, only smaller.
WHO GOT IT RIGHT: George Van, Robert Walker, Andie J, Marc Quinlivan, Robin Campbell, Bob Milligan, Darby Paxton, Mike Tatum, David Evans, JP Weigt, Marika Thiessen, and Yanitz Grinell.