Professor Moriarty is the main antagonist of the animated series Sherlock Hound and the archenemy of the detective Sherlock Hound. This version of the character departs significantly from the literary Moriarty of Arthur Conan Doyle, who rarely appears directly and controls a vast criminal organization from a distance. In Sherlock Hound, Moriarty is a hands-on criminal mastermind who personally organizes and carries out his own schemes, and he appears as the central villain in the majority of episodes. He is depicted as an anthropomorphic gray wolf, a visual detail that sets him apart from the human characters and reinforces his role as a menacing yet often comedic figure.

In terms of background, Moriarty retains the intellectual brilliance associated with the original character but channels it into invention rather than academic work. He is a master inventor and is responsible for much of the steampunk-style technology seen throughout the series. He designs and builds his own machines and gadgets, including a distinctive personal steam car that resembles a cross between a tractor and a tank rather than a conventional automobile. His technological skill means that his crimes often involve elaborate mechanical devices, automated contraptions, and unconventional methods that require Sherlock Hound's keen insight to unravel.

Moriarty's personality is defined by cunning, ambition, and theatrical flair. His plans are frequently complex and outlandish, relying on dramatic and unusual approaches that set the stage for the detective's deductive efforts. Despite his cleverness, his schemes tend to unravel or turn against him, often collapsing as a result of his own overconfidence or Hound's interference. He is persistent and never truly defeated for long, regularly returning with new schemes even after his previous efforts fail.

His motivations center on the pursuit of wealth, grand criminal enterprises, and the desire to outwit Sherlock Hound. Defeating the detective appears to be as important to him as the crimes themselves, making their rivalry deeply personal. On certain occasions, Moriarty sets aside his own ambitions and works as a mercenary for other criminals, lending his skills to objectives he would not normally pursue.

In the story, Moriarty serves as the recurring engine of conflict, driving most of the episodes through his attempted thefts, robberies, and elaborate plots. His relationship with Sherlock Hound is the central dynamic of the series, positioning him as the detective's opposite and equal in intellect, though his morality is fundamentally inverted. Moriarty is also supported by two assistants, Smiley and Todd, who accompany him and help carry out his plans, often bearing the brunt of their failures.

The character shows little dramatic development over the course of the series, remaining a consistent and recognizable antagonist whose methods evolve with each new scheme. His most notable abilities include genius-level intellect, inventive talent, and the capacity to construct advanced machinery. He is also capable of adapting his plans on the move and working directly in the field, rather than operating solely from the shadows. These qualities make him a formidable and enduring opponent for Sherlock Hound, even when his elaborate plans ultimately collapse around him.