A fun fact about Burton is that along with Sylvester Stallone and Burt Young, he was the only other actor to have appeared in all six ‘Rocky’ movies! 
As a life member of the Actors Studio, Burton numbers among his many credits a co-starring role in Frank’s Place and parts in films, such as Stir Crazy and The Toy. He also appeared as Wells, one of the prisoners trapped in the besieged police station in John Carpenter’s 1976 Howard Hawks-inspired action film, Assault on Precinct 13. He later starred in the Rocky films as a trainer to Apollo Creed (Carl Weathers) and Rocky Balboa (Sylvester Stallone). He appeared in an episode of Gibbsville in 1976. Burton also appeared in The Shining and Hook. He had guest appearances in Kojak, The Rockford Files, CHiPs, Twin Peaks, and The A-Team…not too bad!
