In 1993, David Letterman left his post at NBC’s Late Night to host CBS’s Late Show, which would air simultaneously—and in direct competition with—Jay Leno’s The Tonight Show. The titles get confusing. Escalating the chaos was Conan O’Brien, an unknown writer for The Simpsons who was selected to fill Letterman’s vacated spot. To be a novice following Letterman was no easy thing, a fact corroborated by the poor early ratings for Late Night with Conan O’Brien. Yet over 16 years of that show, and then 11 at the helm of a second talk show on TBS, the idiosyncratic O’Brien asserted himself as capable and then beloved. Three years after retiring from his nightly duties, he’s now back with a new four-part travel series, Conan O’Brien Must Go. He’ll explore Norway, Thailand, Argentina, and Ireland. —Jack Sullivan