To answer critics who claimed he was sucessful because he was only playing himself?

Sounds to me like Don Knotts.He was basicly the same sort of character in all his film and TV roles,and many actors only portray characters with extensions of their personalities.

I think the correct answer is "no one". But if this is a trivia question, it is more probable that the questioner was expecting "Andy Griffith" as the "answer".

When Andy started he show, he said it was for 5 years only. He continued to sing this song even as season five began. Don didn't want to be unemployed, so he agreed to do "The Ghost and Mrs. Chicken". Then Andy changed his mind and stayed longer. This is why Don left.

Andy hung around another 3 years, then he left simply because he wanted a change. Eight years is long enough for any gig.

Andy appeared in a couple early episodes of "Mayberry RFD" and one in 1969,but only as a special guest star and was reduced to a minor charachter and then phased out of the seris.