The Human Centipede (First Sequence) is a 2010 Dutch horror film written and directed by Tom Six. The film tells the story of a German doctor who kidnaps three tourists and joins them surgically, mouth to anus, forming a "human centipede". It stars Dieter Laser as the antagonist Dr. Heiter, with Ashley C. Williams, Ashlynn Yennie, and Akihiro Kitamura as the doctor's victims. According to Six, the concept of the film arose from a joke he made with friends about punishing child molesters by stitching their mouths to the anus of a "fat truck driver". Six has also stated that inspiration for the film came from Nazi medical experiments carried out during World War II, such as the actions of Josef Mengele at Auschwitz concentration camp.

When approaching investors prior to filming, Six did not mention the mouth-to-anus aspect of the plot, fearing it would put off potential backers. The financiers of The Human Centipede did not discover the full nature of the film until it was complete. The Human Centipede received mixed reviews from mainstream film critics, but it won several accolades at international film festivals. The film was released in the United States on Video on Demand on April 28, 2010, and on limited release theatrically on April 30. Tom Six began working on a sequel, The Human Centipede (Full Sequence), which is scheduled to be released in 2011.

Lindsay (Ashley C. Williams) and Jenny (Ashlynn Yennie), two American tourists in Germany, are drugged and kidnapped by crazed surgeon Dr. Heiter (Dieter Laser) when they seek help after their car breaks down. The women awake in a makeshift medical ward and witness Heiter informing a kidnapped truck driver (Rene de Wit) that he is "not a match" and killing him. When the women wake up a second time, Heiter has secured a new male captive, Japanese tourist Katsuro (Akihiro Kitamura). The doctor explains that he is a world-renowned expert at separating conjoined twins, but dreams of making new creatures that share a single digestive system. He describes in detail how he will surgically connect his three victims mouth-to-anus. After Lindsay fails in an attempt to escape, Heiter performs the surgery on his victims, placing Lindsay in the middle, Katsuro at the front, and Jenny at the rear. Before beginning the operation, Heiter explains to Lindsay that he had experimented with creating a 'three dog', also joined mouth-to-anus, which died shortly after surgery. Heiter tells Lindsay that the middle dog of his creation experienced the most pain, and as a punishment for her escape attempt she will become the middle part of his centipede.

Once the operation is complete the doctor tries to train his centipede as a pet, and watches with great delight as Lindsay is forced to swallow Katsuro's excrement. However, Heiter eventually becomes irritated after being kept awake by the constant screaming of his victims and realising that Jenny is dying from blood poisoning. When two detectives, Kranz (Andreas Leupold) and Voller (Peter Blankenstein), visit the house to investigate the disappearance of tourists, Heiter decides to add them to his centipede as replacements for Jenny. Heiter fails in an attempt to drug the detectives, and they leave the house to obtain a search warrant. The victims attempt to escape from the ward, crawling up the stairs, and Katsuro attacks Heiter. Their attempt to escape ultimately fails. Katsuro confesses to the doctor, in Japanese, that he deserves his fate because he had treated his family poorly. He then fatally cuts his own throat with broken glass. The detectives return to the house and conduct separate searches, as Heiter hides near his swimming pool. Kranz finds the makeshift ward and then hears a gunshot. He discovers Heiter's victims before finding Voller dead in the swimming pool. Heiter shoots Kranz in the stomach, and Kranz responds by shooting Heiter in the head. Kranz then falls in the pool, dead. Back in the house, Jenny and Lindsay hold hands as Jenny dies from her blood poisoning. Lindsay is left alone in the house, trapped between her deceased fellow captives.