Professor Moriarty is a fictional character in some of the Sherlock Holmes stories written by Sir Arthur Conan Doyle. The character was introduced primarily as a narrative device to enable Doyle to kill Sherlock Holmes, and he only was featured in two of the original Sherlock Holmes stories (though Holmes mentions him in five other stories). Although many adaptations and pastiches give him the first name of James, the first Doyle story to feature him ("The Adventure of the Final Problem") does not give him a first name, whereas the short story "The Adventure of the Empty House" said his first name is James (previously said to be the name of his brother).
Moriarty is a machiavellian, consulting criminal mastermind who does not commit crimes himself but uses his intelligence and network of resources to provide criminals with strategies for their crimes and sometimes protection from the law, all in exchange for a fee or a cut of profit. Holmes likens Moriarty to a spider at the center of a web and calls him the "Napoleon of crime", a phrase Doyle lifted from a Scotland Yard inspector referring to Adam Worth, a real-life criminal mastermind and one of the individuals upon whom the character of Moriarty was based. Despite only twice appearing in Doyle's original stories, later adaptations and pastiches have often given Moriarty greater prominence and treated him as Sherlock Holmes's archenemy.
Professor Moriarty's first appearance occurred in the 1893 short story "The Adventure of the Final Problem" (set in 1891). The story features consulting detective Sherlock Holmes revealing to his friend and biographer Doctor Watson that he has uncovered a secret criminal network responsible for "half that is evil" in London and is on the verge of delivering it a fatal blow. Professor Moriarty is introduced as a criminal mastermind who provides strategy and protection to criminals in exchange for their obedience and a share in their profits. Holmes, by his own account, is originally led to Moriarty by his perception that many of the crimes he investigates are not isolated incidents, but instead the machinations of a vast and subtle criminal organization. Having now gathered and delivered the appropriate evidence to the police, Holmes knows that the network will face justice in a few days, but the mastermind and his trusted lieutenants want to kill him before they are arrested. He flees to Switzlerland, and Watson joins him. The criminal mastermind follows Watson and the consulting detective, and the pursuit ends on top of the Reichenbach Falls, leading to a hand-to-hand fight that apparently ends with both Holmes and Moriarty falling to their deaths. Watson does not see this battle to the death, but finds signs that it happened at the cliff edge near the waterfall, as well as a note Moriarty allowed Holmes to write so he could say goodbye.
In the same story, Holmes describes Moriarty's physical appearance to Watson. According to Holmes, Moriarty is extremely tall and thin, clean-shaven, pale, and ascetic-looking. He has a forehead that "domes out in a white curve", deeply sunken eyes, and shoulders that are "rounded from much study". His face protrudes forward and is always slowly oscillating from side to side "in a curiously reptilian fashion". Holmes mentions that when he and the professor first met in person, Moriarty remarked in surprise, "You have less frontal development that I should have expected," indicating that the criminal believes in phrenology.
Moriarty plays a direct role in only one other Holmes story, "The Valley of Fear" (1914), set before "The Final Problem" but written afterwards. In "The Valley of Fear", Holmes attempts to prevent Moriarty's agents from committing a murder. In a scene in which Moriarty is being interviewed by a policeman, a painting by Jean-Baptiste Greuze is described as hanging on the wall; learning this, Holmes mentions the value of another painting by the same artist to show such works could not have been purchased on a professor's salary. The work referred to is La jeune fille à l'agneau; some commentators have described this as a pun by Doyle on a famous Thomas Gainsborough painting, the Portrait of Georgiana, Duchess of Devonshire, being taken from the Thomas Agnew and Sons art gallery. The gallery believed that Adam Worth was responsible, but was unable to prove the claim.
Holmes mentions Moriarty reminiscently in five other stories: "The Adventure of the Empty House" (the immediate sequel to "The Final Problem"), "The Adventure of the Norwood Builder", "The Adventure of the Missing Three-Quarter", "The Adventure of the Illustrious Client", and "His Last Bow" (the final adventure in Sherlock's canon timeline, taking place years after he has officially retired).
Doctor Watson, even when narrating, never meets Moriarty (only getting distant glimpses of him in "The Final Problem") and relies upon Holmes to relate accounts of the detective's feud with the criminal. Doyle is inconsistent on Watson's familiarity with Moriarty. In "The Final Problem", Watson tells Holmes he has never heard of Moriarty, while in "The Valley of Fear", set earlier on, Watson already knows of him as "the famous scientific criminal".
In "The Empty House", Holmes states that Moriarty had commissioned a powerful air gun from a blind German mechanic surnamed von Herder, which was used by Moriarty's employee/acolyte Colonel Moran. It closely resembled a cane, allowing easy concealment, was capable of firing revolver bullets at long range, and made very little noise when fired, making it ideal for sniping. Moriarty also has a marked preference for organizing "accidents". His attempts to kill Holmes include falling masonry and a speeding horse-drawn vehicle. He is also responsible for stage-managing the death of Birdy Edwards, making it appear that he was lost overboard while sailing to South Africa.
Moriarty is highly ruthless, shown by his steadfast vow to Sherlock Holmes that "if you are clever enough to bring destruction upon me, rest assured that I shall do as much to you". Moriarty is categorised by Holmes as an extremely powerful criminal mastermind adept at committing any atrocity to perfection without losing any sleep over it. It is stated in "The Final Problem" that Moriarty does not directly participate in the activities he plans, but only orchestrates the events or provides the plans that will lead to a successful crime. What makes Moriarty so dangerous is his extremely cunning intellect:
He is a man of good birth and excellent education, endowed by nature with a phenomenal mathematical faculty. [...] But the man had hereditary tendencies of the most diabolical kind. A criminal strain ran in his blood, which, instead of being modified, was increased and rendered infinitely more dangerous by his extraordinary mental powers. [...] He is the Napoleon of crime, Watson. He is the organiser of half that is evil and of nearly all that is undetected in this great city...
Holmes echoes and expounds this sentiment in "The Valley of Fear", stating:
The greatest schemer of all time, the organizer of every devilry, the controlling brain of the underworld, a brain which might have made or marred the destiny of nations—that's the man! But so aloof is he from general suspicion, so immune from criticism, so admirable in his management and self-effacement, that for those very words that you have uttered he could hale you to a court and emerge with your year's pension as a solatium for his wounded character. [...] Foulmouthed doctor and slandered professor—such would be your respective roles! That's genius, Watson.
Moriarty respects Holmes's intelligence, stating: "It has been an intellectual treat for me to see the manner in which you [Holmes] have grappled with this case." Nevertheless, he makes numerous attempts upon Holmes's life through his agents. He shows a fiery disposition, becoming enraged when his plans are thwarted, resulting in his being placed "in positive danger of losing my liberty". While personally pursuing Holmes at a train station, he furiously elbows aside passengers, heedless of whether this draws attention to himself.
Doyle's original motive in creating Moriarty was evidently his intention to kill Holmes off. "The Final Problem" was intended to be exactly what its title says; Doyle sought to sweeten the pill by letting Holmes go in a blaze of glory, having rid the world of a criminal so powerful and dangerous that any further task would be trivial in comparison (as Holmes says in the story itself). Eventually, however, public pressure and financial troubles impelled Doyle to bring Holmes back. While Doyle conceded to revealing that Holmes did not die during "The Final Problem" (as Watson mistakenly concludes), he chose not to undo Moriarty's death in a similar fashion. For this reason, the later novel "The Valley of Fear" features Moriarty as an active villain but is specified to take place before the events of "The Final Problem".
As established in Doyle's canon, Moriarty first gains recognition at the age of 21 for writing "a treatise upon the Binomial Theorem", which leads to his being awarded the Mathematical Chair at one of England's smaller universities. Moriarty later authors a much respected work titled The Dynamics of an Asteroid. After he becomes the subject of unspecified "dark rumours" in the university town, he is compelled to resign his teaching post and leave the area. He moves to London, where he establishes himself as an "army coach", a private tutor to officers preparing for exams. He becomes a consulting criminal mastermind for various London gangs and criminals (it is uncertain if he was already doing this before leaving his teaching post). When multiple plans of his are hampered or undone by Sherlock Holmes, Moriarty targets the consulting detective.
Multiple pastiches and other works outside of Doyle's stories purport to provide additional information about Moriarty's background. John F. Bowers, a lecturer in mathematics at the University of Leeds, wrote a tongue-in-cheek article in 1989 in which he assesses Moriarty's contributions to mathematics and gives a detailed description of Moriarty's background, including a statement that Moriarty was born in Ireland (an idea based on the fact that the surname is Irish in origin). The 2005 pastiche novel Sherlock Holmes: The Unauthorized Biography also reports that Moriarty was born in Ireland, and states that he was employed as a professor by Durham University. According to the 2020 audio drama Sherlock Holmes: The Voice of Treason, written by George Mann and Cavan Scott, Moriarty was a professor at Stonyhurst College (where Arthur Conan Doyle was educated and knew two students with the surname Moriarty).
The stories give contradictory indications about Moriarty's family. In his first appearance in "The Final Problem" (1893), the villain is referred to only as "Professor Moriarty". Watson mentions no forename but does refer to the name of another family member when he writes of "the recent letters in which Colonel James Moriarty defends the memory of his brother". In "The Adventure of the Empty House" (1903), Holmes refers to Moriarty as "Professor James Moriarty". This is the only time Moriarty is given a first name, and oddly, it is the same as that of his purported brother. In the 1914 novel "The Valley of Fear" (written after the preceding two stories, but set earlier), Holmes says of Professor Moriarty: "He is unmarried. His younger brother is a station master in the west of England." In Sherlock Holmes: A Drama in Four Acts, an 1899 stage play, of which Doyle was a co-author, the villain is named Professor Robert Moriarty.
Writer Vincent Starrett suggested that Moriarty could have one brother (who is both a colonel and station master) or two brothers (one a colonel and the other a station master); he added that he considered the presence of two siblings more likely, and suggested that all three brothers were named James. Writer Leslie S. Klinger that suggested Professor Moriarty has an older brother named Colonel James Moriarty in addition to an unnamed younger brother. According to Klinger, writer Ian McQueen proposed that Moriarty does not actually have any brothers, while Sherlockian John Bennett Shaw suggested, like Starret, that there are three Moriarty brothers, all named James. The premise that Professor James Moriarty has two brothers also named James was used in the radio series The Further Adventures of Sherlock Holmes and the manga and anime series Moriarty the Patriot.
"Moriarty" is an ancient Irish name as is Moran, the surname of Moriarty's henchman, Sebastian Moran. Doyle himself was of Irish Catholic descent, educated at Stonyhurst College, although he abandoned his family's religious tradition, neither marrying nor raising his children in the Catholic faith, nor cleaving to any politics that his ethnic background might presuppose. Doyle is known to have used his experiences at Stonyhurst as inspiration for details of the Holmes series; among his contemporaries at the school were two boys surnamed Moriarty.
ln addition to the master criminal Adam Worth, there has been much speculation among astronomers and Sherlock Holmes enthusiasts that Doyle based his fictional character Moriarty on the Canadian-American astronomer Simon Newcomb. Newcomb was revered as a multitalented genius, with a special mastery of mathematics, and he had become internationally famous in the years before Doyle began writing his stories. More to the point, Newcomb had earned a reputation for spite and malice, apparently seeking to destroy the careers and reputations of rival scientists.
Moriarty may have been inspired in part by two real-world mathematicians. If the characterisations of Moriarty's academic papers are reversed, they describe real mathematical events. Carl Friedrich Gauss wrote a famous paper on the dynamics of an asteroid in his early 20s, and was appointed to a chair partly on the strength of this result. Srinivasa Ramanujan wrote about generalisations of the binomial theorem, and earned a reputation as a genius by writing articles that confounded the best extant mathematicians. Gauss's story was well known in Doyle's time, and Ramanujan's story unfolded at Cambridge from early 1913 to mid 1914; The Valley of Fear, which contains the comment about maths so abstruse that no one could criticise it, was published in September 1914. Irish mathematician Des MacHale has suggested George Boole may have been a model for Moriarty.
Jane Stanford, in That Irishman, suggests that Doyle borrowed some of the traits and background of the Fenian John O'Connor Power for his portrayal of Moriarty. In Moriarty Unmasked: Conan Doyle and an Anglo-Irish Quarrel, 2017, Stanford explores Doyle's relationship with the Irish literary and political community in London. She suggests that Moriarty, Ireland's Napoleon, represents the Fenian threat at the heart of the British Empire. O'Connor , 2018, Power studied at St Jarlath's Diocesan College in Tuam, County Galway. In his third and last year he was Professor of Humanities. As an ex-professor, the Fenian leader successfully made a bid for a Westminster seat in County Mayo.
It is averred that surviving Jesuit priests at the preparatory school Hodder Place, Stonyhurst, instantly recognised the physical description of Moriarty as that of the Rev. Thomas Kay, SJ, Prefect of Discipline, under whose authority Doyle fell as a wayward pupil. According to this hypothesis, Doyle as a private joke has Inspector MacDonald describe Moriarty: "He'd have made a grand meenister with his thin face and grey hair and his solemn-like way of talking."
The model which Doyle himself cited (through Sherlock Holmes) in The Valley of Fear is the London arch-criminal of the 18th century, Jonathan Wild. He mentions this when seeking to compare Moriarty to a real-world character that Inspector Alec MacDonald might know, but it is in vain as MacDonald is not so well read as Holmes.
A Sherlockian society was formed by noted Sherlockian John Bennett Shaw called "The Brothers Three of Moriarty", in honor of Professor Moriarty and his two brothers. The group held annual dinners in Moriarty, New Mexico.
Moriarty has been depicted in theater plays, radio broadcasts, films, television series, video games, both manga and anime (Moriarty the Patriot), and various forms of literature.