Conan O'Brien Returns to 'Late Show' After 13-Year Absence to Mock Jay Leno (Video)

Conan Letterman H-2012

Conan O'Brien returned to David Letterman's Late Show after a 13-year absence tonight, and it was only seconds before the name Jay Leno made its first appearance. Leno was reinstated as host of The Tonight Show in early 2010, just seven months after O'Brien had been handed NBC's late night institution. It was a costly and embarrassing battle for the network, and one that Letterman -- who long resented Leno for beating him out as Johnny Carson's Tonight Show successor -- observed with much glee.

In this preview clip, Conan jokes of the reunion, "You know [Leno is] watching right now. He's getting a live feed in a satellite truck right now, watching every second," then launches into his high-squeal Leno impression. Letterman later admits that he was "delighted by everything that happened" in the public fiasco, "except for you losing your job." Finding the silver lining, O'Brien replies: "The only consolation I took during that period was that you were happy." That and his reported $32 million payout, of course.

Watch O'Brien's full Late Show appearance Thursday on CBS at 11:35 p.m. ET.