Letterman’s NBC Spot Goes to Unknown : Television: The network’s late-night choice is Conan O’Brien, a former writer and sketch actor on ‘Saturday Night Live.’

NBC has chosen Conan O’Brien, a producer on “The Simpsons” and a former writer and sketch actor on “Saturday Night Live,” to succeed David Letterman as host of the network’s late-night talk show.

“The Tonight Show” host Jay Leno announced the selection of O’Brien on Monday night’s show.

The 28-year-old O’Brien was the first choice of Lorne Michaels, the “Saturday Night Live” creator who was asked to develop a late-night show after Letterman announced that he was defecting to CBS.

Michaels told NBC executives that O’Brien, who has had only limited public exposure, could represent a new generation of talk-show hosts.

NBC, which initially offered the show to comedian Garry Shandling, has not announced a start date for the new show, which is expected to include several regular comedy sketches in addition to interviews.

Letterman’s last night in the 12:35 a.m. time slot is June 25.

O’Brien won the job after hosting a mock version of the show for NBC executives. He is a 1985 graduate of Harvard University, where he was twice president of Harvard Lampoon magazine.

O’Brien later cut his teeth with the San Francisco-based Groundlings comedy troupe, training in sketch comedy and improvisation.

O’Brien was a writer for HBO’s “Not Necessarily the News” before his five-year stint at “Saturday Night Live,” where he shared a writing Emmy and occasionally appeared as a sketch player.

NBC’s announcement ends conjecture about the network late-night scene that has brewed since Jan. 14, when Letterman announced that he was leaving. His new CBS show will debut on Aug. 23 at 11:35 p.m., opposite Leno.

According to several sources, NBC executives hired O’Brien after Shandling turned the job down on Monday.

Sources said the network made a $20-million, multi-year offer to Shandling to be its new late-night host.

Shandling, who is both the co-creator and star of “The Larry Sanders Show,” a wicked takeoff on talk shows, was said to have been happy doing the HBO series and concerned about both the timing and the creation of a new late-night show for NBC.

NBC executives wanted Shandling to go into production on a show in September or as soon thereafter as possible. He will be in production for the second season of the pay-TV series until August.

Although they were impressed with O’Brien during the mock late-night show held recently on the “Tonight Show” set, NBC entertainment chief Warren Littlefield and other executives had preferred Shandling in part because he is a well-known name who would appeal to NBC affiliates.

Shandling was a frequent “Tonight Show” guest host before Leno took over.