During the 1960s the title was syndicated to television by American International Television. Both The Amazing Colossal Man and its sequel, War of the Colossal Beast (1958) appeared on Mystery Science Theater 3000.
A test explosion of the first atomic plutonium bomb is planned at a military site in Desert Rock, Nevada. When the bomb does not detonate as expected, Lt. Col. Glenn Manning (Glenn Langan) receives orders to keep his men in the protective trench. Moments later, an unidentified small civilian aircraft crash-lands near the bomb site, and Glenn runs into the detonation area to rescue the pilot. Once in the detonation area, the bomb goes off, and Glenn is caught in the atomic blast.
Surviving the blast, but suffering from third-degree burns over almost his entire body, Manning is treated by specialist Dr. Paul Linstrom (William Hudson) and military scientist Dr. Eric Coulter (Larry Thor) at the base hospital. Glenn's fiancée Carol Forrest (Cathy Downs) anxiously awaits a prognosis, but Linstrom refrains from telling her that the consensus is that Glenn will not survive.
The next morning, however, Linstrom and Coulter are stunned to discover that Glenn's burns have completely healed. They begin analyzing the details of Glenn's unusual case. That same evening, Forrest is upset when Glenn's security officer informs her that she is prohibited from seeing Glenn, and she learns that he has been moved to an army rehabilitation and research center in Summit, Nevada. Forrest drives out and is admitted entry, and after overhearing Linstrom and Coulter discussing Glenn's case, Carol lets herself into Glenn's room. She faints in horror when she sees he has mutated into a giant about 16 feet tall.
Linstrom tells Carol that Glenn's exposure to the plutonium blast has caused his old cells to stop dying and his new cells to multiply at an accelerated rate, resulting in his growing proportionately 8 feet in height a day. Linstrom admits that he and Coulter do not know if they can stop Glenn's growth, and that if they don't, he will continue to grow until he dies, but assures her that they will not stop their research.
The following day, Glenn awakens after unsettling dreams of his past. Upon realizing his massive size, Glenn is at first frightened, then deeply disturbed. Carol sees him the next morning to comfort him, but he, now over 22 feet tall, is distant and morose. While the public knows that Glenn survived the explosion, the military has kept the truth of his condition from the media.
As Glenn's body continues to increase in size, Linstrom orders him moved to a tent large enough to provide shelter and recommends that Carol spend time with him. Despite Carol's encouragement, Glenn is angry and bitter. Linstrom eventually reveals that Glenn's heart is growing at only half the rate of his body and soon will be unable to support his enormous size. That night, Carol and Glenn argue over his continuing despair and pessimism; causing Glenn to be upset and yells at Carol to leave him alone.
The following morning as Coulter reports to Linstrom that he may have found a solution to the phenomenal growth, Glenn disappears. The military, headed by Col. Hallock (James Seay), conducts a 10-mile-wide search for the now over 50-foot-tall Glenn, but with no results. When Carol asks Linstrom if she can help in their search for Glenn, he cautions her that Glenn's condition may be affecting his mind. Coulter reveals that he has created a special syringe filled with a serum for Glenn's bone marrow that will stop his growth.
Meanwhile, the local news relays that a "giant man" has been spotted approaching Las Vegas. As the military heads toward Las Vegas, Glenn—now over 60 feet tall and confused—is drawn to the Las Vegas strip. He wreaks havoc on the Royal Nevada, the Silver Slipper, and the Tropicana. At the Sands hotel and after a policeman accidentally fires at him, Glenn picks up a palm tree and hurls it at the crowd, just before smashing the Sands' 56-foot neon sign. When the police become alarmed by Glenn's behavior, they begin firing at him, enraging Glenn, who completely destroys the Pioneer Club's Vegas Vic sign then heads toward Boulder Dam as military helicopters track his movements.
Linstrom, Carol and Coulter attempt to intercept Hallock's troops. After landing at the dam, Coulter and Linstrom take the enormous syringe and plunge it into Glenn's ankle. Glenn removes the syringe, mercilessly spearing Coulter with it. Glenn then picks up Carol and starts across the dam. Using a bullhorn to amplify his message, Linstrom pleads with Glenn to spare Carol, and although he is disoriented, Glenn complies. When Glenn reaches the middle of the dam and releases Carol, Hallock orders his men to fire on him, causing Glenn to tumble into the Colorado River to his apparent death.
Jim Nicholson of American International Pictures had the rights to Homer Eon Flint's 1928 novel The Nth Man, about a man who was 10 miles high. Nicholson thought it could be adapted to cash in on the success of The Incredible Shrinking Man (released six months earlier in 1957) and originally announced Roger Corman as director. Charles B. Griffith was hired to adapt the novel, and he turned it into a comedy. Then Corman dropped out, and Bert I. Gordon was hired. Gordon worked on the script with Griffith, but the collaboration only lasted a day before Griffith quit. Instead, Griffith's regular writing partner Mark Hanna stepped in.
Before Gordon became involved, the film was conceived with Dick Miller in mind for the lead. It was Gordon's first movie for AIP. Principal photography began late in June 1957.
Distributed by American International Pictures (AIP), The Amazing Colossal Man appeared at the top of a program double-bill with Cat Girl. Critical reviews were generally positive with film reviewer Richard W. Nason at The New York Times commenting: "... imaginative story premise." A similar review in Variety, noted: "... Glenn Langan delivers persuasively ... Technical departments are well handled."
In more recent popular internet reviews, on Rotten Tomatoes, The Amazing Colossal Man has had more negative reviews than positive reviews. It holds a 38% from critics and a low 24% from the audience. On the Internet Movie Database, the film has a low score of 4.2/10.
The Amazing Colossal Man and its sequel were featured and riffed on the cult classic mocking show Mystery Science Theater 3000; actor Mike Nelson portrayed the title character twice in the mid-movie host sections of the show's season 3, episodes 9 and 19. On episode 9, the character seems more aggressive to Joel and the bots when the Satellite of Love hit him and nearly proceeds to attack the trio after Tom Servo unintentionally insulted Glenn before leaving when suffering from a brief heart attack, as portrayed in the film.
The Amazing Colossal Man was parodied on Season 1, episode 2, of Robot Chicken in 2005 when a large bald giant, wearing a sarong as a diaper, is struck in the crotch with a wrecking ball as he terrorizes a city, as part of the "Ode to the Nut Shot" sketch.
In Gordon's 1958 film, Attack of the Puppet People, released about six months later, a clip of this film is shown at a drive-in movie theater.
The trailer has also been shown in the film projected at the Disney's Hollywood Studios restaurant, Sci-Fi Dine-In Theater.