I disagree with Ian-Conan O'Brien did not quit-he was fired NBC made a deal with Conan in their 2004 contract negotiations, in which Conan was to become the host of the Tonight Show in 2009.
Conan O'Brien is an American comedian, television host and producer best known for hosting several late-night talk shows for well over two decades, most notably NBC's Late Night with Conan O'Brien