Moriarty the Patriot (Japanese: 憂国のモリアーティ, Hepburn: Yūkoku no Moriāti) is a Japanese mystery manga series written by Ryōsuke Takeuchi and illustrated by Hikaru Miyoshi, based on Arthur Conan Doyle's Sherlock Holmes series. It is a prequel, focusing on the youth of Holmes' nemesis, mathematics prodigy, William James Moriarty. An anime television series adaptation by Production I.G aired from October 2020 to June 2021.

Moriarty is based off his incarnation in the original Sherlock Holmes by the British author Sir Conan Doyle, Professor Moriarty is undoubtedly the most recognizable of Holmes' foes, though he only appears in about two of the sixty Sherlock Holmes stories, with mentions in five others.