David Letterman Retiring From 'Late Show' in 2015

David Letterman, the longest-serving late-night talk show host in TV history, has just announced his retirement.

Letterman made the announcement during the taping of his show Thursday in New York, telling the audience his last show will take place in 2015.

He told the audience ... he's turning 67 and wants to spend more time with his family. Dave went on to say he'd be retiring in the next year or 2. The audience thought he was joking because he said, "Finally Paul and I can get married."

Johnny Depp then came on and told Dave people backstage were weeping. It appears Dave's staff knew of the announcement and many were backstage.

During his announcement, Dave said he started in the business when he was 34 so he's been doing it for half his life, and now it was time to be with his son.

Letterman began his Hollywood career as a stand-up comedian in the late 1970s, appearing several times on "The Tonight Show Starring Johnny Carson." He got his morning show in 1980 and began his late night career in 1982 on NBC with "Late Night with David Letterman."

11 years later in 1993, Letterman moved to CBS to host "The Late Show with David Letterman," after Jay Leno was tapped to replace Johnny Carson on NBC.

Letterman's CBS contract is scheduled to expire next year and Letterman won't be re-upping.