Frank was a gorilla who lived during the latter half of the 20th century. In 1991, he was working as a food server in a restaurant in 'Modern City', made to serve tea and light cigarettes for society ladies. Frank was present when circus owner, Armando, first brought Caesar to the large city. At first, Frank and Caesar did not care for one another, and the two nearly had an altercation while Frank was waiting tables including lighting up a woman's cigarette. Later however, Frank became one of Caesar's followers and actively participated in the ape rebellion against their human masters.
- The role of Frank was played by actor Buck Kartalian. This is the second ape character that Buck has portrayed. He also played the role of Julius in the first film, Planet of the Apes.
- It is possible that Frank is one of the gorilla soldiers seen in the sequel to Conquest, Battle for the Planet of the Apes, but if so, he is never addressed by name. Actor Buck Kartalian does not appear in the movie either.
- Frank is the only gorilla within the franchise to have tan fingers, an error of forgetting to darken Bucks' fingers as the gorilla extras in Conquest had their fingers blackened.