Star Trek: The Original Series the 23rd century bearing a crew dedicated to exploring the Milky Way Galaxy. Roddenberry noted a number of influences on his idea, some of which includes A. E. van Vogt's tales of the spaceship "Space Beagle", Eric Frank Russell's "Marathon" series of stories, and the film "Forbidden Planet" (1956). Some have also drawn parallels with the television series "Rocky Jones, Space Ranger" (1954), a space opera which included many of the elements that were integral to "Star Trek"—the organization, crew relationships, missions, part of the bridge layout, and some technology. Roddenberry also drew heavily from C. S. Forester's Horatio Hornblower
Star Trek: The Original Series who appeared on "The Original Series" later made guest appearances as different characters in later series, most notably Majel Barrett, who not only provided the voice for most Starfleet computers in episodes of every spin-off series (including a single appearance on "", where the computers normally did not speak at all), but also had the recurring role of Lwaxana Troi in "The Next Generation" and "Deep Space Nine". Diana Muldaur, a guest star in the episodes "Return to Tomorrow" and "Is There in Truth No Beauty?" of the original "Star Trek" series, played series regular Dr. Katherine Pulaski in the