Marcel Allain (1885–1969) was a French author who earned a lasting place in literary history through his contributions to crime fiction. He is best remembered today for his collaborative work with Pierre Souvestre, with whom he co-created one of fiction's most enduring antagonists.
Their joint creation, Fantômas, is a legendary fictional arch-villain and master criminal. Through this character, Allain and Souvestre left a significant mark on the thriller genre, establishing a figure that would influence popular culture and crime writing for decades.