From 1959 to 1965, he starred as Teddy in the television Western Rawhide, the show which launched Clint Eastwood's career.
Although generally recognized for his work on He-Man, Erwin has many years of voice acting to his credit (including the voice of Reggie Mantle in Filmation's Archie cartoon), and has provided voices for many productions ranging from television advertisements to live-action movies since the 1960s.
Erwin was the voice of He-Man in the Filmation productions He-Man and the Masters of the Universe and She-Ra: Princess of Power that ran from 1983 to 1986. Due to the extreme cost-cutting by Filmation, the cast of voice actors was small, and Producer Lou Scheimer actually performed the bulk of the character voices. Erwin was also the voice of the henchman character Beast Man, and would on occasion do the voices of other supporting characters, too, such as Webstor and Ram Man.
In 1989, his voice was heard as a radio newscaster in Back To The Future Part II and as a football announcer in the 2000 Disney movie Remember the Titans.