(Adds background; David Letterman, Jimmy Fallon quotes)
By Eric Kelsey
LOS ANGELES, April 10 (Reuters) - Comedian Stephen Colbert, who made his mark satirizing political conservatives on cable television's Comedy Central channel, was named on Thursday to succeed veteran late-night star David Letterman as the host of the CBS "Late Show" next year.
Colbert, 49, currently host of "The Colbert Report," a weeknight show in which he parodies the role of a dim-witted, big-egoed conservative pundit, has signed a five-year agreement with CBS, the network said in a statement.
Details of how the format of "Late Show" will change under Colbert's stewardship, or whether it will remain based in New York City, have yet to be determined.
But Colbert said he will drop his Comedy Central persona, which he first popularized as a member of the cast of "The Daily Show with Jon Stewart." His Emmy-winning "The Colbert Report" debuted in October 2005 and has attracted a strong following among young males, a coveted group that CBS is likely eying with its choice of Colbert.
"I won't be doing the new show in character, so we'll all get to find out how much of him was me. I'm looking forward to it," Colbert told New York Times television writer Bill Carter.
News of Colbert's impending move to CBS marks the latest in a recent shakeup of the late-night television landscape at the major networks as they seek to attract the younger audiences.
Colbert's half-hour show attracts an average of 1.1 million viewers to the Viacom Inc-owned network, according to Nielsen, less than half as many as those who tune into the "Late Show."
Colbert's audience has a median age of 42 years, 16 years younger than Letterman's audience. Ad sales for "The Colbert Report" rose slightly last year while advertising for "Late Show" declined in 2013, according to ad tracking firm Kantar Media.
Jay Leno bid farewell as host of NBC's top-rated "The Tonight Show" in February and was replaced by 39-year-old Jimmy Fallon, who had been following him as host of "Late Night." Fallon in turn was succeeded by Seth Meyers.
"I'd like to welcome the great @StephenAtHome to network late night and also congratulate him on his new name: Jimmy Colbert," Fallon wrote on Twitter, playing on his name as well as ABC's late night host Jimmy Kimmel.
Last week Letterman, 66, announced on his show he was retiring from late-night television sometime next year when his CBS contract expires. Letterman began the "Late Show" on CBS in 1993 after 11 years as the host of NBC's "Late Night" program.
"Stephen has always been a real friend to me," Letterman said in a statement. "I'm very excited for him, and I'm flattered that CBS chose him. I also happen to know they wanted another guy with glasses."
Unlike his late night rivals, Colbert has burnished his image by tackling political issues with the biting satire of his self-described "fool" persona. With his backhanded skewering of conservatives, he has also become a favorite of liberal Americans.
He and Stewart are often ranked as a top source of news for young people and noted for their interviewing skills, often grilling politicians and media personalities.
In 2006, Colbert made waves with his audacious in-character performance roasting the policies of the George W. Bush administration with mock praise at the White House Correspondents Dinner, all within arm's reach of the president.
Colbert tapes his Comedy Central show in Manhattan, but it remained to be seen whether the "Late Show" would stay in its current venue at the nearby Ed Sullivan Theater.
"Simply being a guest on David Letterman's show has been a highlight of my career," Colbert said in a statement. "I never dreamed that I would follow in his footsteps, though everyone in late night follows Dave's lead."
He added: "I'm thrilled and grateful that CBS chose me. Now, if you'll excuse me, I have to go grind a gap in my front teeth," a reference to Letterman's trademark grin. (Additional reporting by Ron Grover; Writing by; Steve Gorman and Eric Kelsey; Editing by Mary Milliken and James Dalgleish)