Jimmy Fallon launched his reign as host of NBC's Late Night program on Monday evening. But first he had to get his predecessor, Conan O'Brien, out of his dressing room during the opening sketch. "I'm about to start my first show," Fallon told O'Brien. "Oh, is that tonight?" O'Brien said. "I was gonna TiVo it, or something." The show also featured appearances by Robert DeNiro and Justin Timberlake, who entertained the audience with his impression of John Mayer's habit of singing with his tongue hanging out of his mouth. Critics called the show uneven but promising. (Photo: WENN)