The Old Man in the Corner is an unnamed armchair detective who appears in a series of short stories written by Baroness Orczy. He examines and solves crimes while sitting in the corner of a genteel London tea-room in conversation with a female journalist. He was one of the first of this character-type created in the wake of the huge popularity of the Sherlock Holmes stories. The character's moniker is used as the title of the collection of the earliest stories featuring the character.

The Old Man relies mostly upon sensationalistic newspaper accounts, with the occasional courtroom visit, and relates all this while tying complicated knots in a piece of string. The plots themselves are typical of Edwardian crime fiction, resting on a foundation of unhappy marriages and the inequitable division of family property. Other period details include a murder in the London Underground, the murder of a female doctor, and two cases involving artists living in "bohemian" lodgings. Another new and noteworthy feature is that no one is ever brought to justice. Though the villains are identified by the narrator (who disdains to inform the police), most cannot be proven guilty beyond a reasonable doubt.