David Letterman to Retire From CBS’ ‘Late Show’ in 2015 (Video)

The late-night space is poised for another shake-up.

After more than 20 years at CBS, David Letterman will announce his retirement as host of the network's Late Show during Thursday night's broadcast. His final show will come in 2015, when his current contract expires. Word of Letterman's departure first surfaced when REM's Mike Mills, one of the show's guests, announced the news on Twitter.  

“The man who owns this network, Leslie Moonves, he and I have had a relationship for years and years and years, and we have had this conversation in the past, and we agreed that we would work together on this circumstance and the timing of this circumstance. And I phoned him just before the program, and I said ‘Leslie, it’s been great, you’ve been great, and the network has been great, but I’m retiring,’” Letterman told his studio audience during Thursday's Late Show taping. 

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He added to a standing ovation in the Ed Sullivan Theater: "We don’t have the timetable for this precisely down – I think it will be at least a year or so, but sometime in the not too distant future, 2015 for the love of God, in fact, Paul and I will be wrapping things up.”

The news comes as Letterman recently surpassed Johnny Carson as the longest-running host in late-night TV history when factoring in his time with CBS' Late Show and his 11-year tenure with NBC on Late Night. Despite long-gestating rumors about Letterman’s future, the host inked a new two-year deal in late 2013. "Les [Moonves] and I had a lengthy discussion, and we both agreed that I needed a little more time to fully run the show into the ground," Letterman quipped in a statement at that time, with Moonves adding: "There is only one Dave, and we are extremely proud that he continues to call CBS home." Moonves long had suggested that Letterman would have the platform as long as he wanted it.

Letterman's exit will provide yet another jolt to a tumultuous landscape, which underwent a massive transformation earlier this year with Jimmy Fallon replacing long-time leader Jay Leno as the host of The Tonight Show. Seth Meyers took over for Fallon on Late Night in late February, exiting from his role with NBC's Saturday Night Live. Given a hefty marketing spend and increased attention, Fallon's arrival has catapulted The Tonight Show over rivals Letterman and Jimmy Kimmel Live (ABC) among the key adults 18-49 demographic.

Since NBC's shakeup, Letterman's Late Night has been averaging 2.85 million viewers -- trailing behind younger, more YouTube-friendly rivals Fallon (4.3 million) and Kimmel (2.7 million), both up year-over-year despite the increase in competition. Amid the renewed late-night wars, Letterman seemed to up his booking game, recently nabbing Lady Gaga for a rare performance and guests including Lindsay Lohan and former president Jimmy Carter

Letterman produces the show through his Worldwide Pants production company, which is also behind his time slot companion The Late Late Show With Craig Ferguson. The banner has also produced scripted fare including CBS' Everybody Loves Raymond

Lesley Goldberg, Lacey Rose