Walter Mitty
An unremarkable or ineffectual person who has fantasies or delusions of grandeur. A reference to the titular character in James Thurber's short story The Secret Life of Walter Mitty. He has been described as the Walter Mitty of the political world, a complete nobody who has somehow contrived a career out of standing on a soapbox and protesting against anything the mainstream politicians do. My father worked for the same company for over 50 years and never even left his home state, but he was always something of a Walter Mitty, dreaming about a life of adventure.
Walter Mitty
A person, generally quite ordinary or ineffectual, who indulges in fantastic daydreams of personal triumphs. For example, He's a Walter Mitty about riding in a rodeo but is actually afraid of horses. This term comes from James Thurber's short story, The Secret Life of Walter Mitty (1939), describing just such a character.