The interocitor, also spelled interositor, is a fictional multi-functional device featured in the original story and 1955 science fiction film This Island Earth. The device arrives in kit form as an intelligence test for scientists who might prove helpful to an alien race.
 This Island Earth
The Interocitor is an alien communications device with unusual and strange properties. The concept was invented by science fiction writer Raymond F. Jones, who wrote the original novel This Island Earth beginning as a series of three sci-fi short stories now known as “The Peace Engineers Trilogy” appearing in the sci-fi pulp magazine Thrilling Wonder Stories from 1949 to 1951. Raymond F. Jones then did a novelization of the complete story into full book form and it was first published in 1952 by Shasta Press. Universal Studios purchased the screen rights to the novel in 1953, since the novel was a popular sci-fi best seller, and made it into a Technicolor film in 1954, which was then released on June 1, 1955. The film was a modest success and has somewhat impressive visual effects. The first third of the trilogy of stories was titled “The Alien Machine”, referring to the Interocitor, with original graphic artwork penned by famous sci-fi artist Virgil Finlay. The story was sold to the press with the help of literary agent Forrest J. Ackerman.
The term interocitor itself, rather than referring to a specific device, likely refers to a general class of devices that share a common set of operating principles (similar to the term computer). This is inferred from the fact an interocitor is observed or described in many different roles:
- Telecommunications device
- Aircraft autopilot
- Surveillance and security controller
- Directed energy weapon
In the film, advanced physicist Cal Meacham first becomes aware of an interocitor when a book arrives at his lab titled Electronic Service, Unit #16. Inside is contained a bill of materials for the interocitor, describing it as, "incorporating greater advances than hitherto known in the field of electronics". From the specifications, Meacham opines, "There's no limit to what it could do. Laying a four-lane highway at the rate of a mile a minute would be a cinch."
Of the 2486 components composing an interocitor, only three are mentioned by name in the film:
- Bead condenser (model #: AB-619)
- Cathermin tube with inindium complex of +4
- Intensifier disk
The instructions accompanying the components also caution that no interocitor part can be replaced, and to bear this in mind while assembling.
Once assembled and powered, Meacham places the intensifier disk into the right-hand control and rotates it 18 degrees counter-clockwise. Upon doing so, the telecommunication function of the interocitor is activated, and Meacham establishes contact with Exeter, the party responsible for sending him the device.
During their conversation, Meacham's lab assistant, Joe Wilson attempts to photograph the device, but is informed by Exeter that "Your camera will pick up nothing but black fog. Images on the interocitor don't register on film."
Meacham later boards a Douglas DC-3 autopiloted by an interocitor to join Exeter at his research facility. Exeter is also seen using an interocitor to remotely observe a private conversation between Meacham and two other scientists at the facility, Ruth Adams and Steve Carlson. Exeter's assistant, Brack, later uses the weapons capability of the device to thwart the attempted escape of Meacham, Adams, and Carlson from the facility.
 Other appearances
- In the game "Borderlands 2", the character Gaige claimed in her personal ECHO recordings that her project (that would eventually be known as Deathtrap) would make her classmate Marcie Holloway's miniature thermosonic generator look like an interocitor.
- Mystery Science Theater 3000: The Movie contained a version of This Island Earth. About halfway through the film, Tom Servo reveals that he has his own interocitor, which the crew uses in an attempt to return to Earth. However, they are foiled first by the inept Metalunan whom they contact, and then by the intervention of Dr. Forrester, who attacks them with his own interocitor.
- An interocitor appeared in the "Weird Al" Yankovic 1989 film UHF and in the music video for his song Dare to be Stupid.
- In the computer-generated television series ReBoot, the interocitor was a component which frequently broke on the car of the main protagonist, Bob.
- In the 2003 film Looney Tunes: Back in Action, the mad scientist found in the California desert is looking for an interocitor that she misplaced.
- Interocitor is the name of a device in Doctor Who, involving quantum telecommunication across time and space. It is named specifically as a reference to this film, and this is mentioned by the Doctor (Peter Davison) during the story. This is in the 2007 audio play Renaissance of the Daleks., it is also mentioned in the 8th Doctor audio story Lucie Miller.
- The short story, A Great Moon Hoax or A Princess of Mars by Ben Bova, starts with an Interocitor being operated by a Martian and an American industrialist to watch old baseball games. The short story is available in Laugh Lines, a collection of short stories available from Baen Books .
- In the 1989 film Arena, a battle droid near the beginning of the film needs a new Interociter unit to be fully repaired.
- A small Interocitor is seen, used, and mentioned by name in the 2011 film, Attack of the Moon Zombies, the sixth in writer/director Christopher R. Mihm's "Mihmiverse" series of modern-made, 1950s-style B-movies.