Red Dragon is a psychological horror novel by American author Thomas Harris, first published in 1981. The story follows former FBI profiler Will Graham, who comes out of retirement to find and apprehend an enigmatic serial killer nicknamed "the Tooth Fairy". The novel introduces the character Dr. Hannibal Lecter, a brilliant psychiatrist and cannibalistic serial killer to whom Graham reluctantly turns for advice and with whom he has a dark past.

The title refers to the figure from William Blake's painting The Great Red Dragon and the Woman Clothed with the Sun. The novel was adapted as a film, Manhunter, in 1986, which featured Brian Cox as Hannibal "Lecktor". Directed by Michael Mann, the film received mixed reviews and fared poorly at the box office, but it has since developed a cult following.

After Harris wrote a sequel to the novel, The Silence of the Lambs (1988), that was turned into a highly successful film of the same name in 1991, Red Dragon found a new readership. The film featured Anthony Hopkins in the role of Hannibal Lecter, for which he won an Oscar for Best Actor in 1991. Due to the success of the film and its sequel, Red Dragon was remade as a film directed by Brett Ratner in 2002, this time bearing the title of the original novel and with Hopkins playing Lecter. Elements of the novel also influenced the NBC television series Hannibal, while the plot was adapted as the second half of the series' third season.

In 1976, Will Graham, a brilliant profiler of the FBI, captured the serial killer Hannibal Lecter, a world-renowned psychiatrist who artistically killed and ate his victims. However, Graham suffered serious injuries from the encounter and retired afterward.

In 1979, a serial killer nicknamed "The Tooth Fairy" stalks and murders seemingly random families during sequential full moons. He first kills the Jacobi family in Birmingham, Alabama, then the Leeds family in Atlanta, Georgia, in both cases breaking into the family home at night, shooting the parents and children, and then having intercourse with the mother's body after she dies, leaving a distinctive bite pattern on her body. Two days after the Leeds murders, Agent Jack Crawford, Graham's mentor, goes to Graham's Marathon, Florida, residence and pleads for his assistance; Graham reluctantly agrees.

After looking over the crime scenes, Graham realizes that the killer posed the family's bodies as an audience during the rape, and accurately predicts the FBI will find the killer's fingerprints on the victims' eyes. He also discovers a stakeout location where the killer watched the home from a nearby wood and discovers a Chinese character carved into a tree: a mahjong symbol known as the red dragon. Having reached a dead end, Graham realizes he must visit Lecter and seek his help to capture "the Tooth Fairy." Lecter, locked in a maximum security cell in the Baltimore State Hospital for the Criminally Insane, offers enigmatic clues to the killer's pathology and cruelly taunts Will that the reason he caught Lecter is because they are alike, disturbing Graham and causing him to cut the meeting short.

"The Tooth Fairy" is revealed (to the readers) to be the production chief of a St. Louis film processing firm named Francis Dolarhyde. He is a disturbed individual obsessed with the William Blake painting The Great Red Dragon and the Woman Clothed with the Sun. Born with a severe cleft palate, Dolarhyde believes himself weak and deformed despite having had corrective surgery. He is unable to control his violent, sexual urges, and believes that murdering people, or "changing" them, as he calls it, allows him to more fully "become" an alternative personality he calls the "Great Red Dragon", after the dominant character in Blake's painting. Flashbacks reveal that his sociopathy is born from the systematic abuse he suffered as a child at the hands of his sadistic grandmother, who raised him after his mother abandoned him as an infant.

As Graham investigates the case, he is hounded by Freddy Lounds, a sleazy tabloid reporter, who publishes an article about Graham consulting Lecter. Dolarhyde, reading the article, writes a fan letter to Lecter, asking for a response. Frederick Chilton, the head of the institute and Lecter's self-styled nemesis, discovers the letter hidden in Lecter's cell, with Dolarhyde's instructions for contacting him removed. After significant forensic analysis, the FBI deduce that Lecter has placed a coded personal ad in Lounds' tabloid, the National Tattler, but are unable to break the code before the publishing deadline, and Graham reluctantly allows the ad to run. Lounds becomes aware of the correspondence and tries to trick Graham into revealing details of the investigation by posing as the killer, but is found out and arrested. When the code is finally broken, it reveals that Lecter has given Graham's address to the killer and tells him to save himself by killing the family. Graham's wife, Molly, and his stepson are evacuated, causing significant tension in his marriage.