Professor Padraic Ratigan is the arch-enemy of Basil of Baker Street and the main antagonist in Walt Disney's 1986 feature film The Great Mouse Detective.

He is the story's version of Professor James Moriarty from Arthur Conan Doyle's Sherlock Holmes stories, and serves as the adversary to the Sherlock Holmes counterpart Basil of Baker Street. He has cited the "Big Ben Caper" and the "Tower Bridge Job" as two of his most notorious criminal operations.

Physical Description
Ratigan is a towering rat with gray fur dressed in a dark gray suit complete with a long black cape with a red underside. His face is shaven and has yellow eyes with lavender circles around them, above them are thick eyebrows. Although he lavishes himself as a mouse, he has rat-like characteristics, such as sharp fangs and fingers, a large nose, and a long, pink tail. On his head, he wears a black top hat with a gray band, which covers his black combed hair. His suit includes a high white collar and a gray vest with buttons on it with a pink-and-purple striped cravat. On his hands are white gloves and cuffs with golden cufflinks. He is always seen carrying a gold cane.

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Ratigan in his vicious, highly feral state.
However, when Ratigan becomes completely enraged, he becomes incredibly feral, running on all fours in a hunched position. His hair becomes messy and his clothes become torn exposing his intimidating physique as Ratigan becomes vicious as he obtains a more rat-like appearance. His nails and teeth also grow longer and gnarly.

Personality
“Oh, I love it when I'm nasty.”
―Ratigan[src]
Ratigan has a variety of henchmen that follow him, including his overweight pet cat Felicia, Bill the Lizard, a small mouse named Bartholomew, and his right-hand man, a peg-legged bat named Fidget. Personality-wise, Ratigan is very charismatic, calm, and calculating, but can easily be sent into a violent rage at the mention of Basil or by the incompetence of his minions. He has a very dark, malicious sense of humor and an inflated ego. Unlike most Disney villains, Ratigan is an ebullient, lip-smacking jester who has a tendency towards big movements and long rants or speeches.

Even though he is one, Ratigan detests, above all else, being referred to as a rat, preferring the description of a "big mouse," and fed Bartholomew to Felicia when Bartholomew calls him the "world's greatest rat" while intoxicated. He can easily be identified as a rat since he has five-fingered hands, while all the other mice have four fingers. Also, the mice in the movie have fur-covered tails that much thinner than Ratigan, who has a pink, fleshy segmented tail. Despite his hatred of being labeled as such, he possessed enough self-control to barely react when Basil referred to him as a rat, which is evidenced with two instances in the film: The first, right after he trapped Basil and Basil called him a sewer rat, Ratigan retained his cool demeanor, only closing his watch, and the second time, when Basil revealed his survival after the literal breaking down of the fake Queen of Moustoria by finishing her sentence of Ratigan being a rat, only growling in irritation. In the Basil of Baker Street book series, Ratigan's first name is revealed to be Padriac, and he is in fact, portrayed as a mouse (in contrast to his depiction in the movie).