This document analyzes the competitive history between comedians Jay Leno and David Letterman. It details how they both started in Los Angeles comedy clubs in the late 1970s and later became guests on Johnny Carson's "The Tonight Show". When Carson retired in 1992, Leno was given "The Tonight Show" hosting role instead of the expected Letterman. In response, Letterman began hosting "The Late Show" on CBS in the same time slot. This began a long-running rivalry as the two competed for viewers and ratings that helped define the era of late night talk shows.