Grey as Lino (as Duane Gray) Richard Gilden Raoul Koom Martin Garralaga as Old Native Villager Patrick O'Moore as Dr. Willoughby William Hamel as Mr. Trainer Charles H. Gray as Jim Wheatley (as Charles Gray) Charles Postal as The Butler And: The King of the Calypso, Sir Lancelot Production The project was originally known as Beyond Terror. Sir Lancelot signed to appear in the film to take advantage of the calypso craze. It was the first of an eight-picture deal between Charles Marquiss Warren's Emirau Productions and 20th Century Fox. The Unknown Terror was filmed during late March and early April 1957 at what Powers called "the old Producers Studio" in Hollywood. The film's working title was Beyond Terror, of which Powers said, "I think that might have been a better title." According to the American Film Institute (AFI), the name and composer of the song performed by Sir Lancelot during the movie is unknown. Music for the film is listed in the credits as being by Raoul Kraushaar, but without mention of individual pieces of music. Release The Unknown Terror was the first film on a double-bill with Back from the Dead, both of which were made by Regal Films and were released in the US on August 12, 1957. The pressbook for the films refers to them as "2 Supermonstrous Superhuman Supershockers!" When the film was released in the UK in October 1957, it was granted an A-certificate by the British Board of Film Censors. An "A-Cert" meant that the film was considered to be "more suitable for adults." The Unknown Terror opened in Sweden on December 1, 1957 and in Mexico and Greece at unspecified dates. Twentieth Century Fox distributed the film to theaters in the UK and the US. The film went into television syndication through National Telefilm Associates in 1960. In Chicago, for example, it was shown repeatedly after 1964, when WBBM-TV instituted "Science Fiction Wednesdays" as part of the station's Early Show daily movie series, shown at 4:00 pm Central Time, which had been on the air since the 1950s. It was also shown regularly on Chicago's WGN-TV film series Creature Features in various time slots and on various days, usually starting between 10:30 pm and 1:25 am Central Time. The movie was not available for individual home viewing until 2004, when Teakwood Studios put on sale an "unauthorized" release in VHS and DVD