Planet of the Apes (1968 film) was well received by critics and audiences, launching a film franchise, including four sequels, as well as a short-lived television show, animated series, comic books, and various merchandising. In particular, Roddy McDowall had a long-running relationship with the "Apes" series, appearing in four of the original five films (absent, apart from a brief voiceover, from the second film of the series, "Beneath the Planet of the Apes", in which he was replaced by David Watson in the role of Cornelius), and also in the television series. The original series was followed by Tim Burton's remake "Planet of the Apes" in
Escape from the Planet of the Apes the second. A new character of Dr. Milo is introduced played by actor Sal Mineo, who hoped his career would gain from the new project much as McDowall's career had from participating in the first film. Charlton Heston, star of the first film and supporting actor in the second, appears in this third installment only in two brief flashback sequences. Despite "Beneath the Planet of the Apes" ending in a way that seemed to prevent the series from continuing forward, 20th Century Fox still wanted a sequel. Roddy McDowell, in the franchise documentary "Behind the Planet of the Apes", stated