First appeared in League of Extraordinary Gentlemen #4 in 1999. Professor James Moriarty is a criminal and the archenemy of Sherlock Holmes who secretly worked for the MI5 and formed the League of Extraordinary Gentlemen on their behalf. Moriarty is the main antagonist of Alan Moore's eponymous comic series. He is loosely based on the character from Sir Arthur Conan Doyle's The Final Problem.