For Whom the Bell Tolls
Comrade Andre Marty
Also known as "The Crazy," Comrade Marty is a very well-known French Communist and the Commissar of the International Brigades (to which Robert Jordan belongs). He's turned bitter and paranoid after years of party struggles and thwarted ambition, and likes killing just about everyone he can get his hands on because he's convinced they're insubordinates. Real historical figure, by the way.