Leno wraps up his 17-year-run as host of NBC's late-night show on May 29. The network says that O'Brien will be Leno's final guest. Then O'Brien steps in as "Tonight" host June 1.
The big names making the cut for Leno's final week of shows include Mel Gibson, Prince and Billy Crystal -- who was Leno's first guest when he took "Tonight" over from Johnny Carson in 1992.
Carson's final guests were Bette Midler and Robin Williams, who appeared on Carson's next-to-last show. He hosted his final "Tonight" broadcast without guests.
This fall, Leno will begin a daily prime-time show for NBC.