Born in Brookline, Massachusetts, O'Brien was raised in an Irish Catholic family. He served as president of "The Harvard Lampoon" while attending Harvard University, and was a writer for the sketch comedy series "Not Necessarily the News". After writing for several comedy shows in Los Angeles, he joined the writing staff of "Saturday Night Live". O'Brien was a writer and producer for "The Simpsons" for two seasons until he was commissioned by NBC to take over David Letterman's position as host of "Late Night" in 1993. A virtual unknown to the public, O'Brien's initial "Late Night" tenure received unfavorable reviews and remained on a multiweek renewal cycle during its early years. The show generally improved over time and was highly regarded by the time of his departure in 2009. Afterwards, O'Brien relocated from New York to Los Angeles to host his own incarnation of "The Tonight Show" for seven months until network politics prompted a host change in 2010. After this departure, O'Brien hosted a 32-city live comedy tour, which was the subject of the documentary, "Conan O'Brien Can't Stop". He then hosted "Conan" from 2010 to 2021. He has also hosted such events as the Emmy Awards and "Christmas in Washington".