Talk show host David Letterman announced that he will retire from the "Late Show" in 2015. He will have hosted it for 22 years after his retirement. In 1993, Letterman began his show at the Ed Sullivan Theater in New York City. He also hosted "Late Night" on NBC for 11 years before being replaced by "The Tonight Show" with Johnny Carson.

Letterman is expected to announce his big news on Thursday night, according to NY Daily News. R.E.M. bass guitarist Mike Mills confirmed Letterman's news on his Twitter account. Mills will perform on Thursday night's episode.

Letterman had signed his most recent contract through 2015, and he never gave any hint as to whether it would be his last one.

It is still unknown what Letterman will say about his decision as reported by CNN. His fellow late night show host, Jay Leno, also retired from the "Tonight Show" on NBC. Leno was replaced by Jimmy Fallon.