Christina Applegate and O'Brien in 1998

Late Night with Conan O'Brien is an American late night television talk show featuring a comic as host and various celebrity guests. Talk shows like Late Night have been a staple of the television industry for many years, due to inexpensive production costs, particularly free celebrity guests that promote their latest films, records or other projects. The only significant variable in the talk show formula is the host, currently Conan O'Brien.

Given how difficult hosting a talk show is, once a talk show host succeeds, they are rarely replaced after the first three months, and typically serve for more than a decade.

Late Night has followed The Tonight Show on the NBC network for decades. The Tonight Show, which is shown in most markets just after the local late evening news, has always had more viewers than Late Night, and was the first late night talk show on NBC. However, Late Night has always had a stronger hold on the much sought-after 25 to 35 age bracket than the Tonight show, which tends to attract older viewers.

In 1993, O'Brien replaced David Letterman, long time host of the Late Night with David Letterman, when Letterman lost a power struggle with Jay Leno to replace retiring Johnny Carson as host of the Tonight Show. CBS hired Letterman for a new show called the Late Show that directly competes with the Tonight Show, continuing the sucession struggle for the title of dominant late night talk show.

O'Brien moved to Late Night from The Simpsons in 1993, where he served as a script writer. The entertainment industry has long believed the Simpsons executives assembled the best commedic script writing talent available. O'Brien wrote four episodes of The Simpsons, including Homer Goes to College and Marge vs. the Monorail.

Conan's show also launched the career of Robert Smigel's Triumph the Insult Comic Dog.