The Crawling Eye is an independently made 1958 British black-and-white science fiction film drama. It was produced by Robert S. Baker and Monty Berman and directed by Quentin Lawrence.
The film is based on a 1956 British ITV "Saturday Serial" television program. The film was distributed in the UK by Eros Films Ltd. as The Trollenberg Terror, and in the US by Distributors Corporation of America as The Crawling Eye. In the US it was released as a double feature with the UK film Cosmic Monsters (a.k.a. The Strange World of Planet X).
On the Swiss mountain Trollenberg, one of three student climbers is suddenly killed, his head ripped from his body. Two sisters, Anne (Munro) and Sarah Pilgrim (Jayne), a London mind-reading act, are travelling by train to when Anne faints as the train passes the mountain. Upon waking, Anne insists that they must get off at the next stop.
UN troubleshooter Alan Brooks (Tucker), in the same train compartment as the sisters, goes to Trollenberg's observatory, where Professor Crevett (Warren Mitchell) explains that, despite many climbing accidents, no bodies are ever found; an always-stationary radioactive cloud is regularly observed on the mountain's south face. Brooks learns that similar incidents took place in the three years earlier, before a similar radioactive cloud vanished without a trace. Local rumors circulated that something was living in the mist.
Anne is giving a mind-reading demonstration at the hotel when she "sees" two men in a base camp hut on the mountain: Dewhurst (Stuart Saunders) is asleep when the other man, Brett (Andrew Faulds), under some kind of mental compulsion, walks outside. Meanwhile, the cloud has enveloped the hut. Anne suddenly faints again, and Brooks phones the hut but no one answers.
A rescue party ventures to the hut looking for both men. Anne, in a trance-like state, urges the rescuers to stay away. Inside the hut, the group discover that everything is frozen solid, despite the hut being locked from the inside. Dewhurst's body is found under the bed, its head missing. A arrives and circles overhead, and a man is seen off in the distance. At his location, the first rescuer there finds a with a severed head inside. He is quickly set upon and killed by Brett, who later attacks and kills a second rescuer.
Now at the hotel, Brett storms in and launches an attack on Anne. The men manage to subdue him, and during the struggle Brett sustains a severe head gash, but no blood flows from the wound. Brett is heavily sedated and locked away. Brooks recalls a similar incident in the Andes that followed a similar pattern: a man murdered an elderly woman who allegedly possessed psychic abilities just like those displayed by Anne. The killer's body was discovered to have been deceased for at least 24 hours prior to his murder of the old women. Brett escapes his improvised cell and resumes his hunt for Anne, this time armed with a small hand axe. Before he can reach Anne, he is quickly shot and killed by Brooks.
The cloud has begun to move down the mountainside towards the hotel, so the group retreats to the heavily fortified observatory. As they enter the cable car, a mother realizes that her young daughter is missing. In a thickening mist a giant, multi-tentacled creature with a single huge eye appears at the hotel, smashing down the front door. Brooks manages to rescue the child from the lobby, both of them narrowly escaping its grasp. They return to the cable car, but the delay has given the thickening mist a chance to reach the car platform. The transport motor begins to freeze, starting and stopping, the cable slipping, but the cable car arrives safely. The single cloud has now split and become four while converging on the observatory.
Hans (Colin Douglas), who left the hotel, suddenly turns up at the observatory. Once inside, he begins exhibiting the same obsession with Anne. Hans tries to strangle her, but the group can only stop him by killing him. As the tentacled monsters near the observatory, everyone makes to combat them. By radio, Alan orders an aerial firebombing raid against the observatory, which has a reinforced concrete roof and walls that can withstand the assault.
Journalist Philip Truscott (Payne) strikes one of the creatures with a Molotov cocktail, setting it ablaze. He is caught from above by one of the tentacled monsters on the observatory's roof. With another Molotov cocktail, Brooks sets that one ablaze, forcing the burning creature to release Truscott. Later, Truscott does the same as another one-eyed monster manages to breach a thick wall, trying to get at Anne. The aerial firebombing assault begins and is successful at torching the remaining creatures. 
- Forrest Tucker as Alan Brooks
- Laurence Payne as Philip Truscott
- Jennifer Jayne as Sarah Pilgrim
- Janet Munro as Anne Pilgrim
- Warren Mitchell as Crevett
- Frederick Schiller as Klein
- Andrew Faulds as Brett
- Stuart Saunders as Dewhurst
- Colin Douglas as Hans
- Derek Sydney as Wilde
- Leslie Heritage as Carl
- Theodore Wilhelm as Fritz
- Jack Taylor as Jim
- This film is adapted from a television serial broadcast on ITV in 1956. The film retained the same director, as well as Laurence Payne in the role of Philip Truscott and Stuart Saunders as Dewhurst. Otherwise, it has an entirely different cast and crew.
- The Trollenberg Terror is the final film produced by Southall Studios, one of the earliest pioneer film studios in the UK, and is one of the last films released by Distributors Corporation of America.
- Mitchell's role was originally meant to be played by Anton Diffring, but Diffring pulled out of the part shortly before shooting began.
- A year before he did this movie, Forrest Tucker starred in a movie called The Abominable Snowman of the Himalayas, in which he confronted psychic Yetis.
- John Carpenter has said that this film, with its creatures hidden in the clouds, was the inspiration for his film The Fog (1980).
- This film (including the opening titles sequence) was parodied in the first season of the Warner Bros. TV cartoon Freakazoid! as "The Cloud." In it, victims were turned into clowns rather than being killed.
- The Crawling Eye monster makes an appearance in Stephen Kings's horror novel It. The child protagonists encounter a manifestation of the creature in the sewers during a segment of the novel set in 1958.
- The Crawling Eye was nominated in The Golden Turkey Awards series for "Most Idiotic Ad Lines in Hollywood History" for "The nightmare terror of the slithering eye that unleashed agonizing horror on a screaming world!" It lost to Kwaheri.
- As Mike Nelson, Crow, and Tom Servo settle in their new apartment on Earth at the very end of the final MST3K episode (at the time) - Diabolik - The Crawling Eye comes on the television as Mike and the bots sit down to watch, bringing the show full circle to the beginning of its cable run. Crow comments that the movie looks familiar.