The films listed below have been ranked by a number of critics in varying media sources as being among the worst films ever made in the 20th century. Examples of such sources include Metacritic, Roger Ebert's list of most-hated films, The Golden Turkey Awards, Leonard Maltin's Movie Guide, Rotten Tomatoes, pop culture writer Nathan Rabin's My World of Flops, the Stinkers Bad Movie Awards, the cult TV series Mystery Science Theater 3000 (alongside spinoffs Cinematic Titanic, The Film Crew and RiffTrax), and the Golden Raspberry Awards (aka the "Razzies"). Films on these lists are generally feature-length films that are commercial/artistic in nature (intended to turn a profit, express personal statements or both), professionally or independently produced (as opposed to amateur productions, such as home movies), and released in theaters, then on home video. There are 57 films listed below, with 103 across both lists.

1930s

Maniac (1934)

Maniac, also known as Sex Maniac, is a pre-Code exploitation-horror film directed by Dwain Esper. The story is a loose adaptation of the Edgar Allan Poe story "The Black Cat" and follows a vaudeville impersonator who becomes an assistant to a mad scientist. Promoted as a documentary on mental illness, Maniac was criticized for its gratuitous footage of women undressing and for plagiarizing horror sequences from the 1922 silent film Häxan. Danny Peary believes that Maniac is the worst film ever made, and Charlie Jane Anders of Gawker Medias io9 described it as "possibly the worst movie in history." Rotten Tomatoes placed Maniac on its list of movies "So Bad They're Unmissable", Vanity Fair included the film on its list of the 20 worst movies ever and it is featured in John J. B. Wilson's book The Official Razzie Movie Guide: Enjoying the Best of Hollywood's Worst.

Reefer Madness (1936)

Reefer Madness (originally released as Tell Your Children and sometimes titled or subtitled as The Burning Question, Dope Addict, Doped Youth, and Love Madness) is a 1936 American exploitation film and propaganda work revolving around the melodramatic events that ensue when high school students are lured by pushers to smoke cannabis and consequently become addicted and involved in various crimes such as a hit and run accident, manslaughter, murder, attempted rape, descent into madness, association with organized crime, and suicide.

Pacific Standard wrote that Reefer Madness was "one of the first films ever to be considered transcendentally bad" and Leonard Maltin has called it "the grand-daddy of all 'Worst' movies". News.com.au considered it a "disastrous flop turned cult classic" due to its "terrible acting and exaggerated drug-addicted stereotypes". Natalli Amato of The Daily Dot included Reefer Madness on her list of the best worst movies, writing that it "may be one of the worst movies of all time for the fact that it accomplished the exact opposite of its intended goal" by becoming a cult classic among stoners. Leaflys Danté Jordan also wrote that it may be "the worst movie of all time", criticizing its many inaccuracies regarding marijuana use and calling it "easily one of the most uncreative and tone-deaf pieces of anti-cannabis propaganda".

The Terror of Tiny Town (1938)

The Terror of Tiny Town, directed by Sam Newfield and produced by Jed Buell, remains the only musical Western with an all-dwarf cast. The film was pulled from obscurity as a camp classic after appearing in college and midnight screenings in the early 1970s. In 1978, it was included in Michael Medved's book The Fifty Worst Films of All Time, and it has since been listed as one of the worst films ever made by Flavorwire, Rotten Tomatoes, and The Golden Turkey Awards. Melvin Defleur referred to it as "Perhaps the worst film of all time", and critic Gabriel Ricard listed it as the worst film ever made; stating, "not only is it pretty terrible, but Tiny Town is also pretty endearing." In 1986, The Terror of Tiny Town was the first film featured on Canned Film Festival, a late night television show featuring the worst movies ever made.

1940s

The Babe Ruth Story (1948)

The Babe Ruth Story is a 1948 baseball film biography of Babe Ruth, starring William Bendix, Claire Trevor and Sam Levene. The New York Times describes it as "the Plan 9 from Outer Space of baseball biopics". It was rushed into release while Ruth was still alive. One infamous scene features Ruth promising a dying child that he will hit two home runs; the child is subsequently cured of his ailments after Ruth delivers on the promise.

Baseball Hall of Famer Ted Williams believed it to be the worst movie he had ever seen. The Washington Times stated that it "stands as possibly the worst movie ever made". The Spokesman-Review included the film on its list of the worst films of all time, while Paul Newberry of the Associated Press wrote that the film's place on "nearly every list of the worst movies ever made" was "with good reason". Newsdays Jack Mathews similarly wrote that The Babe Ruth Story was "what many people consider to be the worst sports movie of all time". It also was called one of the worst sports films ever, by both Newsday and The A.V. Club, and called one of the worst biopics by Moviefone and Spike. Entertainment writer Michael Sauter included the film in his book, The Worst Movies of All Time, and Leonard Maltin called it "perfectly dreadful".

No Orchids for Miss Blandish (1948)

No Orchids for Miss Blandish, a British gangster film adapted from the 1939 novel by James Hadley Chase, received a very hostile reception from the press. This was mainly due to the film's high (for the time) implied level of violence and rape, but also because its attempt to portray Americans using a largely British cast (including an early role for Sid James) was seen as unconvincing.

The British film journal Monthly Film Bulletin called it "the most sickening exhibition of brutality, perversion, sex and sadism ever to be shown on a cinema screen". The Sunday Express film reviewer called No Orchids for Miss Blandish "the worst film I have ever seen". The Australian newspaper The Age also gave a harsh review: "No Orchids for Miss Blandish is not only a disgrace to the studio that made it, but it also reflects on the British industry as a whole ... the entire production is unpardonable."

Cliff Goodwin, discussing No Orchids for Miss Blandishs initial reception, notes it was "unanimously dubbed 'the worst film ever made. Later reviews of the film were equally antipathetic. No Orchids for Miss Blandish was described by British film reviewer Leslie Halliwell as a "hilariously awful gangster film ... one of the worst films ever made". Leonard Maltin's Classic Movie Guide states that No Orchids for Miss Blandish "aspires to be a Hollywood film noir and misses by a mile."

Despite (or because) of the condemnation, the film was commercially successful"Outrage: No Orchids for Miss Blandish" by Brian McFarlane in British Crime Cinema, edited by Steve Chibnall, Robert Murphy. Routledge, 1999. (pg. 37-50). and broke box office records in Britain in areas where it was not banned.Robert Murphy, Realism and Tinsel: Cinema and Society in Britain 1939-48 2003 p210

1950s

Glen or Glenda (1953)

Glen or Glenda starred Ed Wood as Glen, a transvestite who cross-dresses as Glenda. Wood also directed the film. After a dream sequence, Glen undergoes psychotherapy to help "cure" him of his transvestism.

Leonard Maltin wrote that Glen or Glenda was worse than Wood's later Plan 9 from Outer Space and considered it "possibly the worst movie ever made". Julien Allen of Reverse Shot similarly wrote that it was "widely considered to be an atrocity" and "the most catastrophic failure of [Wood's] singularly bad career". Richard Barrios described Glen or Glenda as "one of the funniest and worst movies ever made".Richard Barrios, Screened Out: Playing Gay in Hollywood from Edison to Stonewall, Psychology Press, 2003, , Page 235.

Robot Monster (1953)

Robot Monster is a science-fiction film produced and directed by Phil Tucker and originally shot and exhibited in 3D. Its title character, which is "a man in a gorilla suit wearing what looks like a diving helmet sprouting TV antennae", was given the Most Ridiculous Monster in Screen History award in The Golden Turkey Awards. It is also featured in The Book of Lists 10 worst movies list, The Fifty Worst Films of All Time and Michael Sauter's book The Worst Movies of All Time. Robot Monster was featured in an episode of the movie-mocking TV show Mystery Science Theater 3000, as well as Canned Film Festival. The film is remembered fondly by horror novelist Stephen King, who quotes, and agrees with, a review in Castle of Frankenstein magazine ("certainly among the finest terrible movies ever made", "one of the most laughable poverty row quickies"). Chris Barsanti in The Sci-Fi Movie Guide writes: "[Robot Monster] gives Plan 9 From Outer Space a run as the worst movie of all time."

The Conqueror (1956)

Howard Hughes funded The Conqueror, an epic film featuring John Wayne as Mongolian chieftain Genghis Khan and the redheaded Susan Hayward as a Tatar princess. The movie was filmed near St. George, Utah, downwind from a nuclear testing range in Nevada, and is often blamed for the cancer deaths of many of the cast and crew, including Hayward, Wayne, Agnes Moorehead, Pedro Armendáriz, and director Dick Powell. In addition to filming near the testing range, truckloads of the red sands were transported back to the studios for interior scenes and by 1980, 91 of the 220 (over 41%) cast and crew members had been diagnosed with cancer.

The film made the ten-worst list in The Book of Lists, appears in Michael Sauter's The Worst Movies of All Time, and was among those listed in The Fifty Worst Films of All Time. Additionally, the Aldergrove Star described The Conqueror as the worst ever made and Complex listed it as the worst biopic ever made. The Guardian called the choice of Wayne for Khan – a role originally written for Marlon Brando – "one of the worst casting decisions of all time". Despite Wayne having lobbied for the lead role after reading the script, he later lamented having taken it, stating, "Don't make an ass of yourself trying to play parts you are not suited for." The Daily Telegraph writes: "by absolutely every conceivable metric – financially, critically, historically, ethnically, and even body count – it would come to be known as one of the biggest disasters in cinematic history." Rolling Stone described the film as the worst decision in movie history.

Hughes, one of the world's wealthiest people at the time, had previously produced the successful dramatic films Hell's Angels, Scarface, and The Outlaw. After viewing The Conqueror, Hughes bought every existing print for $12 million and refused to let the film be seen on TV until 1974, reportedly out of guilt over the decision to shoot at such a hazardous location. This was the last film Hughes produced.

Fire Maidens from Outer Space (1956)