Brian Stack leaving ‘Conan’ for Stephen Colbert’s ‘Late Show’

Brian Stack, the Chicago-trained comic writer who has been a key voice on Conan O’Brien’s three late-night shows on and off the air, is taking up with a new funnyman.

He announced his exit from TBS’ Los Angeles-based “Conan” Thursday on Twitter, and his writing room colleague Andres du Bouchet tweeted later that Stack will be heading to New York to join “Late Show With Stephen Colbert.”

Stack, who grew up in Palatine and appeared on the stages of iO and Second City, joined NBC’s “Late Night With Conan O’Brien” in 1997 and followed O’Brien to his ill-fated turn on “The Tonight Show” and then to his current cable series. A nimble performer himself, he has turned up regularly on all three shows, as memorable characters including an aggressive door-to-door salesman, a caped dork who interrupts O’Brien’s every statement and the ghost of a racist 1940s crooner.

A Second City alum himself, Colbert is scheduled to take over CBS’ “Late Show” on Sept. 8. David Letterman, who created the show in 1993, steps down May 20.

• Another comedy writer on the move is Chicago’s own Peter Grosz, who told his Facebook friends on Thursday that it was his last day on NBC’s “Late Night With Seth Meyers.” Best known for his Sonic commercials with T.J. Jagodowski, Grosz added, “I’m leaving to act more and write my own projects, in case you’re tempted to ask.”