Little Big Man

Little Big Man is the title of a 1964 Thomas Berger novel and its 1970 film adaptation starring Dustin Hoffman, following a white man raised by the Cheyenne who claims to be the sole survivor of Custer's Last Stand.

The phrase itself suggests someone of small stature but outsized importance or self-regard—a little man who looms large.

As a general expression, it can describe anyone whose influence exceeds their apparent status, or ironically, someone with inflated self-importance.