Dr. Maximus was a character in the original Planet of the Apes film. An orangutan, the highest caste of apes portrayed in the movie, Dr. Maximus is the Commissioner for Animal Affairs ("Animal" meaning "Human" in the apes' lexicon).
Dr. Zaius brings Dr. Maximus to the laboratory where the scientists Cornelius and Zira have given safe haven to human astronaut Taylor. As Commissioner of Animal Affairs, Dr. Maximus notes that the chimpanzees are breaking the leash law and orders that Taylor be removed from the area, which is restricted to apes.
Dr. Maximus appears as part of the National Academy tribunal that presides over the hearing that accuses the two scientists of surgically enabling Taylor to speak. As Dr. Maximus explains, the purpose of the hearing is "to settle custodial and jurisdictional questions concerning this beast, and determine what's to be done with him." As the first seated judge, Dr. Maximus covers his eyes when the three orangutans mime the "See No Evil, Hear No Evil, Speak No Evil" adage in one of the film's many satirical flourishes. (According to the film's star, Charlton Heston, director Franklin Schaffner conceived the idea but was reluctant to film it, fearing it would be perceived as lowbrow and incongruous with the seriousness of the scene.)