TV host David Letterman to retire next year

David Letterman will retire next year ending the longest career in American late-night television hosting and sparking a debate about who will replace him in the high-profile slot on the CBS network.

Letterman announced during Thursday's recording of his Late Show that he had earlier told CBS president Leslie Moonves of his intention to retire to stunned silence from his studio audience who appeared unable to spot the seriousness of the pronouncement during his routine banter.

Without saying when he would leave a show he has fronted since 1993, Letterman, who turns 67 next week and has presented almost 6,000 shows over 34 years in various TV slots, said he would leave some time during 2015. The audience eventually responded with a sustained standing ovation.

His departure follows the recent retirement of long-standing rival Jay Leno from NBC's Tonight show and will leave the 11.35pm slot on three television networks filled with a new generation of hosts. Jimmy Fallon (39) replaced Leno and Jimmy Kimmel (46) moved to the time slot on ABC.

Near-instant media speculation named daytime talk show host Ellen DeGeneres, Stephen Colbert, host of Comedy Central's The Colbert Report, popular awards show host Neil Patrick Harris and fellow CBS chat show presenter Craig Ferguson as possible replacements.

With the razor-sharp wit and expert comic timing that made him and his show a staple in American TV entertainment, Letterman made his announcement, saying that he had always said: “When this show stops being fun, I will retire 10 years later.”