There have been two conflicts regarding the hosting duties of NBC's The Tonight Show, both involving Jay Leno.
1992 Tonight Show conflict, between Leno and David Letterman 2010 Tonight Show conflict, between Leno and Conan O'Brien
See also
Jay Leno David Letterman Conan O'Brien Late Night with David Letterman Late Night with Conan O'Brien The Tonight Show with Jay Leno The Tonight Show with Conan O'Brien Late Show with David Letterman Conan (talk show)