David Letterman's last 'Late Show' date set

David Letterman -- who launched "Late Show" on August 30, 1993 -- will step down as host on May 20, 2015, the network announced Wednesday. The possible relevance of that date: It will be almost 23 years to the day that Letterman's idol and mentor, Johnny Carson, left "The Tonight Show" on May 22, 1992.

"David Letterman has given to all of us a remarkable legacy of achievement and creative brilliance that will never be forgotten," said Leslie Moonves, President and CEO of CBS Corp. in a statement. "It's going to be tough to say goodbye, but I know we will all cherish the shows leading up to Dave's final broadcast in May."

Indeed, Letterman, 67, created something that was far from certain on that long ago summer night -- a nightly comedy and variety series that could hold its own against TV's most successful dynasty, "The Tonight Show." It managed that and far more over its nearly 22 years, including a run as late night leader early in the show's history.

Letterman's first late-night outing began on Feb. 1, 1982, when he launched NBC's "Late Night" franchise. When he steps down, he will have hosted 6,028 episodes of both "Late Night" and "Late Show," according to CBS.

Letterman announced he was stepping down from "Late Show" in April. Stephen Colbert, who ends his "Colbert Report" on Dec. 18, will take over next year; but no launch date has yet been set.