Professor Moriarty is the principal antagonist of the anime Sherlock Hound and the archenemy of the detective Sherlock Hound. He is an anthropomorphic gray wolf and a loose adaptation of the literary figure Professor James Moriarty, reimagined here as an active, hands-on criminal rather than a distant mastermind.

In terms of background, this version departs sharply from the original stories. Whereas the literary Moriarty rarely appears and operates through a vast criminal network, this Moriarty personally involves himself in his schemes and is revealed as the perpetrator behind nearly every crime in the series. He is a gifted inventor, responsible for much of the unusual steampunk technology seen in the show, including a distinctive steam-powered vehicle that resembles a cross between a tractor and a tank, which he uses in his escape attempts. He is usually accompanied by two assistants, Smiley and Todd, who is also known as George.

His personality is defined by a combination of genuine intellectual brilliance, vanity, and a flair for the theatrical. He takes evident pride in his own cleverness and devises elaborate, often outlandish plans that rely on unconventional methods and intricate machinery. At the same time, his schemes are frequently so complicated that they collapse under their own weight, and they are routinely thwarted or turned back against him, usually through the intervention of Sherlock Hound. This pattern gives him a comic, almost endearing quality despite his villainous role, and he never seems to learn from his repeated failures, returning with fresh ambition in episode after episode.

His motivations are primarily greed and the desire to execute spectacular thefts, but his rivalry with Sherlock Hound is equally important. He is driven by a need to prove his superiority over the detective, and their conflict forms the central recurring dynamic of the series. Occasionally he also takes on jobs as a mercenary for other criminals, pursuing objectives that fall outside his usual interests when the payment or challenge appeals to him.

Within the story, he functions as the main antagonist and the direct opposite of the hero. His presence guarantees conflict in most episodes, and his clever but flawed inventions and getaways provide the series with much of its energy. His relationship with Sherlock Hound is one of mutual opposition: Hound is the only figure consistently capable of unraveling his schemes, and Moriarty is the only criminal truly worthy of Hound's attention. His dealings with Smiley and Todd are those of a boss commanding two loyal but bumbling subordinates, who carry out his orders and often suffer the consequences when plans go wrong. He also regularly clashes with the police, whom he generally outwits until Hound steps in.

As a recurring villain, he undergoes little personal development. His character remains essentially consistent throughout the series, with no major changes to his goals or personality. Instead, his development is expressed through the escalating ambition and inventiveness of his plans. His defining abilities are his inventive genius and mechanical skill, which allow him to create the strange devices and vehicles featured in the show, as well as his talent for constructing complex strategies that, while impressive in design, consistently prove to be his own undoing.