Tracer Bullet is a recurring, though rarely-seen, character in Calvin and Hobbes. He is one of Calvin's alter-egos.
The character, a private investigator based on any number of film noir and detective novel clichés, makes his first appearance in a story arc in which Calvin gets a bowl haircut courtesy of Hobbes. When Calvin was forced to wear a hat to cover his bad haircut, the alter-ego was born, and he would appear in a total of three story arcs.