Ellery Queen's Mystery Magazine is a bi-monthly American digest size fiction magazine specializing in crime fiction, particularly detective fiction, and mystery fiction. Launched in fall 1941 by Mercury Press, EQMM is named after the fictitious author Ellery Queen, who wrote novels and short stories about a fictional detective named Ellery Queen. From 1993, EQMM changed its cover title to be Ellery Queen Mystery Magazine, but the table of contents still retains the full name.

Mystery is a fiction genre where the nature of an event, usually a murder or other crime, remains mysterious until the end of the story. Often within a closed circle of suspects, each suspect is usually provided with a credible motive and a reasonable opportunity for committing the crime. The central character is often a detective, who eventually solves the mystery by logical deduction from facts presented to the reader. Some mystery books are non-fiction. Mystery fiction can be detective stories in which the emphasis is on the puzzle or suspense element and its logical solution such as a whodunit. Mystery fiction can be contrasted with hardboiled detective stories, which focus on action and gritty realism.