Radio personality and journalist known for his work as a daytime host of current events programming on LBC. He's also appeared on the Channel 5 show 5 Talk and BBC Two's Newsnight.
He attended the London School of Economics and started his career with the Daily Express, publishing under the publication's oft-used synonym William Hickey.
He's also written for Cosmopolitan and The Spectator and started broadcasting with Channel 5 in 2000.
He married Lucy McDonald O'Brien in 2000. They have two daughters together.
Frank Lampard once called into O'Brien's show to discuss tabloid rumors that were swirling around the footballer.