Factbox: Key dates in Conan O'Brien/Jay Leno shakeup

LOS ANGELES (Reuters) - NBC and Conan O'Brien have agreed to end his brief stint in the coveted role as host of "The Tonight Show," opening the way for previous host Jay Leno to return to that position. Following is a look back at how this real-life NBC drama unfolded and was resolved.

* 1992, Leno takes over the hosting job of late-night talk program "The Tonight Show" from TV legend Johnny Carson after serving as a replacement host since 1987. David Letterman, who had been one of Leno's rivals for the job, becomes his key competitor on network CBS.

* 1993, NBC hires O'Brien to host "Late Night," a program that followed "The Tonight Show."

* 2004, NBC announces that O'Brien will take over for Leno as host of "The Tonight Show" in 2009.

* December 2008, NBC announces that Leno, whose "The Tonight Show" is late night's No. 1 program, will host a new one-hour show at 10 p.m. weekdays, a move aimed partly to reduce the costs of producing scripted dramas at that time. The move was considered an experiment as such a talk show had not aired in those lucrative prime-time hours.

* June 1, 2009, O'Brien takes over as host of "The Tonight Show."

* He draws 9.2 million viewers that day but over time his ratings plunge and average 2.8 million viewers from June to December, according to Nielsen. Leno averaged 5 million in his last season. Letterman's "The Late Show" on CBS becomes No. 1 in late night for the first time since 1995.

* September 15, 2009, "The Jay Leno Show" debuts at 10 p.m. and goes on to average 5.8 million viewers an episode, lower than the average in that period.

* On January 10, faced with pressure from affiliates who said "The Jay Leno Show's" poor viewership led to lower ratings for their 11 p.m. newscasts, NBC confirms it will abandon the 10 p.m. show. Instead, NBC will air Leno's show at 11:35 p.m. after local news, and move "The Tonight Show with Conan O'Brien" to 12:05.

* On January 12, O'Brien says he will not host his version of "The Tonight Show" after Leno, putting him and NBC in talks to end his contract.

* On Jan 20, NBC reaches a $45 million deal with O'Brien under which he leaves the Tonight Show and Leno again takes over. Of that amount, $32.5 million will go to O'Brien and about $12 million to his staff, people with knowledge of the deal say.

(Reporting by Alex Dobuzinskis: Editing by Bob Tourtellotte and David Storey)