This article is for Sir Arthur Conan Doyle's character. For other versions of the character see Versions of James Moriarty.
James Moriarty
Pd Moriarty by Sidney Paget
Vital statistics
Sex Male
Died 4 May, 1891
Nationality British
Family Colonel James Moriarty (brother)
Occupation Mathematician
Criminal mastermind
Behind the scenes
Appearances "The Final Problem"
The Valley of Fear
"His Last Bow" (mentioned)
"He is the Napoleon of crime, Watson. He is the organizer of half that is evil and of nearly all that is undetected in this great city. He is a genius, a philosopher, an abstract thinker. He has a brain of the first order. He sits motionless, like a spider in the centre of its web, but that web has a thousand radiations, and he knows well every quiver of each of them."
Sherlock Holmes to Dr Watson speaking about Professor Moriarty [src]

Professor James Moriarty, the arch-enemy of the famous Detective Sherlock Holmes, a mathematics professor turned the world's only consulting criminal. His genius is equal to, if not perhaps greater than, Holmes himself.

Despite only appearing in two stories, Moriarty has been proven to be the most dangerous of all criminals that Holmes has ever encountered. In the short story "The Adventure of the Final Problem", during a fight with Holmes above the Reichenbach Falls, Moriarty fell to his death.


Professor Moriarty's first appearance and his ultimate end occurred in Doyle's story "The Final Problem", in which Holmes, on the verge of delivering a fatal blow to Moriarty's criminal ring, is forced to flee to the Continent to escape retribution. The criminal mastermind follows, and the pursuit ends atop the Reichenbach Falls, during which, Moriarty falls to his death while fighting with Holmes. During this story, Moriarty is depicted as something of a Mafia Godfather: he protects nearly all of the criminals of England in exchange for their obedience and a share in their profits. Holmes, by his own account, was originally led to Moriarty by the suggestion that many of the crimes he perceived were not the spontaneous work of random criminals, but the machinations of a vast and subtle criminal ring. In such a way, he is described as a Consulting Criminal, the opposite of Holmes, a Consulting Detective.

Moriarty plays a direct role in only one other of Doyle's Holmes stories: The Valley of Fear, which was set before "The Final Problem," but published afterwards. In "The Valley of Fear", Holmes attempts to prevent Moriarty's agents from committing a murder. Moriarty does not meet Holmes in this story. In an episode where Moriarty is interviewed by a policeman, a painting by Jean-Baptiste Greuze is described as hanging on the wall; Holmes remarks on another work by the same painter to show it 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 upon the name of Thomas Agnew of the gallery Thomas Agnew and Sons, who had a famous painting stolen by Adam Worth, but was unable to prove the fact.

Moriarty's family and first name

The stories give a number of contradictory indications about the Professor's family. In his first appearance in "The Adventure of the Final Problem", Moriarty is only referred to as Professor Moriarty, with no first name mentioned. Watson does, however, 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."


Professor Moriarty was an extremely intelligent person. He is mentioned by Holmes himself as having a mind of the first order. He was a mathematical and scientific genius, having studied at university and having his work on the Binomial Theorem being globally acclaimed. Moriarty, unfortunately, possessed a lust for power that led to criminal practices.

Professor Moriarty impresses Holmes, who is not easily impressed, with his incredible talent at organising elaborate crimes throughout London whilst keeping his own identity and involvement effectively anonymous from the authorities. However, Moriarty's personality speedily developed into that of a calculative, sociopathic megalomaniac.

When he appears in The Final Problem, he is introduced as a ruthless, cunning and decisively malicious person. He expresses his intelligence to Holmes, but also his profound ruthlessness. Moriarty admits that physically duelling with Holmes is considered an extreme measure on his part, but is still entirely willing to resort to it - this means that he is completely willing to go beyond his comfort zone if need be. He is also shown to be abundantly self-confident.

Moriarty's malevolence is shown when, after his famous first encounter with Holmes, he arranges three ways of trying to kill Holmes but simultaneously make it look coincidental or accidental.


Sherlock Holmes described him as The Napoleon of Crime. Moriarty was a criminal genius, as smart as Holmes himself (and possibly smarter). He possessed the phenomenal talent for organising criminal activities to perfection throughout a city as powerful and widespread as London. Although an older man, and given to dealing with problems using his brains rather than brawn, he was clearly an excellent hand-to-hand fighter when pushed. Despite his frail and aging appearance, he was a surprisingly skilful fist-fighter, able to give the extremely strong and martial arts-proficient Holmes a run for his money when they fought atop the Reichenbach Falls.


Holmes described Moriarty as follows:

"He is a man of good birth and excellent education, endowed by nature with a phenomenal mathematical faculty. At the age of twenty-one he wrote a treatise upon the binomial theorem which has had a European vogue. On the strength of it, he won the mathematical chair at one of our smaller universities, and had, to all appearances, a most brilliant career before him. 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. Dark rumours gathered round him in the University town, and eventually he was compelled to resign his chair and come down to London. 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. He is a genius, a philosopher, an abstract thinker. He has a brain of the first order."
―Holmes in "The Final Problem"

Holmes echoes and expounds this sentiment in The Valley of Fear stating:

"But in calling Moriarty a criminal you are uttering libel in the eyes of the law — and there lie the glory and the wonder of it! The greatest schemer of all time, the organizer of every deviltry, 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. Is he not the celebrated author of The Dynamics of an Asteroid, a book which ascends to such rarefied heights of pure mathematics that it is said that there was no man in the scientific press capable of criticizing it? Is this a man to traduce? Foulmouthed doctor and slandered professor — such would be your respective roles! That’s genius, Watson. "
―Holmes in The Valley of Fear

Character significances

Moriarty has several interesting notes as a character in the Sherlock Holmes franchise:

  • He is very much the mirror image of Holmes himself: both of them are geniuses among their breed, are extremely resourceful, are sophisticated and commit their activities to prevent boredom. However, whilst Holmes is a detective, Moriarty, in contrast, is a criminal.
  • Moriarty is the only adversary that Holmes genuinely fears and admires (Which is also the way Moriarty views Holmes).
  • Moriarty is the only villain who drives Holmes the closest to fleeing for his life
  • He was only introduced at all so that Conan Doyle could move on from the character of Sherlock Holmes.
  • The idea of the clash between Holmes and Moriarty throughout 'The Final Problem' inspires the notion that Sherlock Holmes went down destroying his true rival. Also, the idea that Holmes went down, ridding the world of the most dangerous and powerful criminal minds of the age - and, against all odds and at the cost of his own life, prevailing over the criminal.


Moriarty has been portrayed in several adaptations of Sherlock Holmes, including novels, films, and TV shows. He is often considered Holmes' arch-enemy, even though he is not a major character in the majority of the original stories.

In other works

  • Professor Moriarty is portrayed twice in "Star Trek: The Next Generation." Once in the episode "Elementary, Dear Data" and again in "Ship in a Bottle". He is created as the only fitting enemy for Data, an android, while he is pretending to be Sherlock Holmes on the Holodeck, a kind of virtual reality recreation area. The computer accidentally makes the character sentient, and in doing so chaos ensues.
  • Moriarty was seen in the PC game Sherlock Holmes: The Awakened, in which Moriarty had survived falling off Reichenbach and is in a weakened condition in a Swiss hospital.
  • Moriarty was also in the game The Testament of Sherlock Holmes - part of the Adventures of Sherlock Holmes (game series) - plotting to frame Sherlock and take over Britain. 
  • In "The League of Extraordinary Gentlemen", a team of literary heroes is recruited to confront a dangerous villain, who just happens to be Professor James Moriarty.