Conan Christopher O'Brien is an Irish American comedian. He has been host of the television program Late Night with Conan O'Brien on the NBC network since 1993. He is slated to succeed Jay Leno as the host of The Tonight Show in 2009.

O'Brien was born in Brookline, Massachusetts, a suburb of Boston. He is the third of six children and one of four boys. A Roman Catholic, he was a lector at St. Ignatius Parish. His father, Dr. Thomas O'Brien, was a research physician at Brigham and Womens' Hospital and an associate professor at Harvard Medical School. His mother, Ruth Reardon O'Brien, is a former well-known lawyer at the Boston law firm of Ropes & Gray. His sister Jane is a comedy writer and producer. O'Brien is a distant cousin of Denis Leary through marriage; contrary to popular belief, they are not actually related through a recent common ancestor.

On January 12, 2002, O'Brien married advertising executive Liza Powell in Seattle, Washington, in a nuptial Mass at St. James Cathedral by Father Paul O'Brien (no relation). They have one daughter, Neve, born on October 14, 2003 in New York City.