Playing the character of Dr. Zaius in the animated series "Return to the Planet of the Apes" was Richard Blackburn's only foray into voice acting. Blackburn is best noted for his co-screenwriting talent behind the hit independent movie "Eating Raoul."
Of course, The character of Zaius is based on Zaius from Planet of the Apes and Beneath the Planet of the Apes, and on Zaius from the TV Series. The orangutan leader of the ape scientific community, is depicted as a grandfatherly politician who questions the tactics of General Urko.
Blackburn also voiced one of the astronauts in the series, Bill Hudson, who, with two other astronauts are hurtled into the future and found themselves stuck in a world populated by advanced apes and primitive humans. As with the live action television series, the animated series was concluded before the resolution of the storyline, and we do not learn if the astronauts are able to return to their own time period. But the animated series does otherwise offer a conclusion. Doctor Zaius, in recognising the threat of a military overthrow from General Urko, assures that he is relieved of command. Further, Cornelius and Zira, in recognising that Simian Society was established long after human society had deteriorated, believed that the time was right for humans to be offered equal rights to that of apes, and intend to present their proposition to the Senate.

The series ran from September 6 - November 18, 1975.