Liza Rowe

O'Brien was born on April 18, 1963 in Brookline, Massachusetts. His father, Thomas Francis O'Brien, is a physician, epidemiologist, and professor of Medicine at Harvard Medical School. His mother, Ruth O'Brien (née Reardon), is a retired attorney and former partner at the Boston firm Ropes & Gray.

O'Brien attended Brookline High School, where he served as the managing Editor of the school newspaper, The Sagamore. In his second year, O'Brien was an intern for Congressman Robert Drinan and in his senior year, he won the National Council of Teachers of English writing contest with his short story, "To Bury the Living". After graduating as valedictorian in 1981, he entered Harvard University. At Harvard, O'Brien lived in Holworthy Hall during his first year and Mather House during his three upper-class years. He concentrated in history and literature and graduated magna cum laude in 1985. O'Brien's senior thesis concerned the use of children as symbols in the works of William Faulkner and Flannery O'Connor. During college, O'Brien briefly served as the Drummer in a band called "The Bad Clams", was a Writer for the Harvard Lampoon humor magazine, and developed a spoof of the popular video game One on One: Dr. J vs. Larry Bird in which the Boston Celtics play against a classical ballet troupe. During his sophomore and junior years, he served as the Lampoon's President. At this time, O'Brien's Future boss at NBC, Jeff Zucker, was serving as President of the school's newspaper The Harvard Crimson.

He has been a staunch Democrat since casting his first vote for President in 1984 for Walter Mondale. He considers himself a moderate on the political spectrum. O'Brien's longtime friend and former dormmate in Mather House at Harvard is Father Paul B. O' Brien, with whom he founded Labels Are For Jars, an antihunger organization based in Lawrence, Massachusetts, and helped open the Cor Unum meal center in 2006. The two are not related.

O'Brien moved to Los Angeles after graduation to join the writing staff of HBO's Not Necessarily the News. He was also a Writer on the short-lived The Wilton North Report. He spent two years with that show and performed regularly with improvisational groups, including The Groundlings. In January 1988, Saturday Night Live's executive Producer, Lorne Michaels, hired O'Brien as a Writer. During his three years on Saturday Night Live (SNL), he wrote such recurring sketches as "Mr. Short-Term memory" and "The Girl Watchers"; the latter was first performed by Tom Hanks and Jon Lovitz. O'Brien also co-wrote the Sketch "Nude Beach" with Robert Smigel, in which the word "penis" was said or sung at least 42 times. While on a writers' strike from Saturday Night Live following the 1987–88 season, O'Brien put on an improvisational comedy revue in Chicago with fellow SNL Writers Bob Odenkirk and Robert Smigel called Happy Happy Good Show. While living in Chicago, O'Brien briefly roomed with Jeff Garlin. In 1989, O'Brien and his fellow SNL Writers received an Emmy Award for Outstanding Writing in a Comedy or Variety Series.

From 1991 to 1993, O'Brien was a Writer and Producer for The Simpsons. When O'Brien first arrived at the Fox lot, they temporarily gave him Writer Jeff Martin's office. O'Brien was nervous and self-conscious, feeling that he would embarrass himself in front of what he regarded as an intimidating collection of Writers. O'Brien would pitch characters in their voices as he thought that was the norm until Reiss informed him that no one did such. He fit in quickly, commanding control of the room frequently; Josh Weinstein called it a "ten-hour Conan show, nonstop". According to John Ortved, one of his fellow Writers ventured that if Conan hadn't left to do Late Night, he was a shoo-in to take over as showrunner on The Simpsons.

Late Night with Conan O'Brien, originating from Studio 6A at 30 Rockefeller Plaza in New York City, premiered September 13, 1993 to unfavorable reviews from contemporary critics. This reception was not completely unsurprising; O'Brien wrote a self-deprecating New York Times piece titled "O'Brien Flops!" on the day of the show's premiere. Critics attacked O'Brien: Tom Shales of The Washington Post suggested that "the host resume his previous identity, Conan O'Blivion." Generally, critics viewed O'Brien as nervous and fidgety on-camera, and that he was "too smart, too East Coast, too sophisticated, too young and even too tall to be successful." The show was constantly at risk for cancellation; at one low point in 1994, NBC threatened to put him on a week-to-week contract. Executives were anxious to replace him with Greg Kinnear, who followed O'Brien with Later at 1:30 am. Interns filled empty seats in the audience while affiliates began to inquire about replacement hosts. In one installment after a short stretch of reruns, sidekick Andy Richter described his vacation activities as follows: "I sat back and reminded myself what it's like to be unemployed." The in-joke referenced the rumors floating in the trades that NBC was near canceling the program.

Twice Conan has served as the master of ceremonies for the White House Correspondents' Association dinner in Washington, D.C., in 1995 and again in 2013.

O'Brien's audience, largely young and male (a coveted demographic), grew steadily and the show began to best competitors in the ratings, which it would continue to do for 15 seasons. In the early days of the Internet, fans launched unofficial websites, compiling precise summaries of each episode. Even Tom Shales was a convert: he called the show "one of the most amazing transformations in television history." Beginning in 1996, O'Brien and the Late Night writing team were nominated annually for the Emmy Award for Best Writing in a Comedy or Variety Series, winning the award for the first and only time in 2007. In 1997, 2000, 2002, 2003, and 2004, he and the Late Night writing staff won the Writers Guild Award for Best Writing in a Comedy/Variety Series. In 2001, he formed his own television production company, Conaco, which subsequently shared in the production credits for Late Night.

Things would improve slowly. Banter between O'Brien and Richter improved, and sketches grew in popularity ("If They Mated", "Desk Drive", "In the Year 2000"). A reliable staple involved a TV screen, lowered behind O'Brien's desk and displaying a still photo of news figure. The lips and voice of these characters – frequently a party-crazed hillbilly interpretation of Bill Clinton – were supplied by writing partner Robert Smigel. A turning point was David Letterman's February 1994 appearance. "It was a morale boost," said O'Brien. "I'm thinking, If the guy who created the 12:30 thing comes on and says we're smart and funny, let's go." The show went through a temporary wobble in January 1995 when Robert Smigel, feeling burned out, quit as head Writer. The show's quality improved slowly over time, and most credit O'Brien's growing comedic performance. Within a year, a comedic formula began to arise: the show would combine the lewd and wacky with a more elegant, narrative-driven remotes. Regular characters would typically include a "Masturbating Bear" and a famous remote found Conan visit a historic, Civil War-era baseball league. That piece was one of O'Brien's personal favorites, later remarking, "When I leave this earth, at the funeral, just show this, because this pretty much says who I'm all about."

O'Brien, like many SNL Writers, occasionally appeared as an extra in sketches; his most notable appearance was as a doorman in a Sketch in which Tom Hanks was inducted into the SNL "Five-Timers Club" for hosting his fifth episode. O'Brien returned to host the show in 2001 during its 26th season. O'Brien and Robert Smigel wrote the television pilot for Lookwell starring Adam West, which aired on NBC in 1991. The pilot never went to series, but it became a cult hit. It was later screened at The Other Network, a festival of unaired TV pilots produced by Un-Cabaret; it featured an extended interview with O'Brien and was rerun in 2002 on the Trio network.

O'Brien met Elizabeth Ann 'Liza' Powel in 2000, when she appeared on Late Night with Conan O'Brien in an advertising skit involving Foote, Cone & Belding, where she worked as senior copywriter. The couple dated for nearly 18 months before their 2002 marriage in Powel's hometown of Seattle. O'Brien and Powel have a daughter, Neve (born October 14, 2003) and a son, Beckett (born November 9, 2005). O'Brien often affirms his Irish Catholic heritage on his show. On a 2009 episode of Inside the Actors Studio, he stated that ancestors from both sides of his family moved to America from Ireland starting in the 1850s, subsequently marrying only other Irish Catholics, and that his lineage is thus 100% Irish Catholic.

As of October 2005, Late Night with Conan O'Brien had for eleven years consistently attracted an audience averaging about 2.5 million viewers. The apotheosis of the Late Night remotes centered on the realization in 2006 that O'Brien bore a striking resemblance to the then female President of Finland, Tarja Halonen. "We took the show to Helsinki for five days," O'Brien recalled, "where we were embraced like a national treasure."

Starting in September 2006, O'Brien was stalked by Father David Ajemian of the Archdiocese of Boston, who, despite multiple warnings to stop, sent O'Brien letters signed as "your priest stalker" and came into contact with O'Brien's parents. O'Brien and Ajemian had attended Harvard University at the same time. Frustrated that he had been denied a spot in the Late Night audience, Ajemian sent a letter to O'Brien stating that he flew to New York "in the dimming hope that you might finally acknowledge me." He stated in another letter, "Is this the way you treat your most dangerous fans??? You owe me big time, pal." In another letter, Ajemian seemed to make a death threat, saying, "Remember Frank Costello once dodged a bullet in your building and so can you."

Ajemian then tried to forcefully enter a taping of Late Night but was caught and arrested. He was previously warned by the NBC security team to stay away from the studio. After a psychological evaluation, he was deemed fit to stand trial. He was bailed out of jail. He was then reported missing by his father on November 10, 2007. He was found and underwent evaluation at a hospital. He was again found fit to stand trial on April 4, 2008. On April 8, Ajemian pleaded guilty to stalking, stating that he "never meant to cause anxiety or to upset anyone." He was ordered to pay a $95 court charge and to sign a two-year restraining order barring him from coming near O'Brien.

On September 11, 2008, Ajemian checked himself out of his treatment at a hospital against the wishes of his bishop, Seán Patrick O'Malley. Cardinal O'Malley then released a statement saying that, because he violated his bishop's wishes, Ajemian could no longer serve as a priest in the Catholic Church. In late 2010, Ajemian was charged with harassing the TV host Anthony Everett while violating a restraining order.

O'Brien purchased a $10.5-million mansion in Brentwood, Los Angeles, California, to prepare for his move there in 2009 from New York City to host The Tonight Show at Universal Studios Hollywood. As part of a long-running gag, he brought his 1992 Ford Taurus SHO with him to California, showcasing it on both the inaugural episodes of The Tonight Show and Conan.

In January 2008, after his show was put on hold for two months owing to the strike by the Writers Guild of America, he reemerged on late-night TV sporting a beard, which guest Tom Brokaw described as making him look like "a draft dodger from the Civil War." After leaving The Tonight Show with Conan O'Brien on January 22, 2010, O'Brien again grew a beard, which he kept until May 2, 2011, when it was partially shaved on the set of his TBS talk show, Conan, by Will Ferrell with battery-operated clippers (and completely shaved off-screen by a professional barber). The event was dubbed on the show as "Beardocalypse", and included a contest for fan-submitted artwork.

On October 21, 2011, O'Brien was ordained as a minister by the Universal Life Church Monastery, allowing him to perform a same-sex marriage while back in New York, then one of the few states in the US where gay marriage was legal, to tape a week's worth of shows. The wedding, between a member of O'Brien's staff and his partner, was held on the stage of the Beacon Theatre on November 3, 2011, and broadcast on Conan.

O'Brien provided the voice of talk show host Dave Endochrine in the 2013 DC Universe animated original movie Batman: The Dark Knight Returns (Part 2).

O'Brien hosted the 2014 MTV Movie Awards on April 13, 2014 at the Nokia Theatre L.A. Live.

In February 2015, following the onset of the Cuban Thaw, O'Brien became the first American television personality to film in Cuba for more than half a century. Conan O'Brien then visited Armenia. In April 2016, O'Brien visited South Korea in response to a fan letter urging him to visit, as well as a growing fan base online. His visit included a trip to the Korean Demilitarized Zone, which resulted in O'Brien and Steven Yeun to also 'visit' North Korea by stepping across the border line at the DMZ. Conan commented on the significance during the Sketch, claiming, "The idea that you and I could be in North Korea, talking and communicating freely, seems like kind of a cool message."