After beginning his career in show business as a disc jockey, Dermot O'Leary became a presenter at the British-owned public service station, Channel 4. While working for Channel 4, O'Leary presented shows that were geared towards young adults, ages 16 to 34. His popularity among that age group ultimately landed him the hosting position for Channel 4's "Big Brother's Little Brother," which featured interviews and behind-the-scenes outtakes from the popular "Big Brother "reality series. O'Leary hosted additional "Big Brother"-themed spinoffs, including 2007's "Big Brother: Celebrity Hijack," before leaving the series indefinitely in January of 2008. However, O'Leary continued hosting British television programs, most notably the game show, "1 vs. 100," and the talent competition, "The X Factor" where he replaced host Kate Thornton. In March of 2009 O'Leary played an unlikely role in music history, after introducing Michael Jackson at The O2 Arena in London. However, it would prove to be Jackson's final public appearance before his untimely death in June of that year. When he's not hosting television shows, O'Leary is also a widely respected radio host. Since 2004 he has hosted a radio program on the BBC, which features both new music and live performances with recording artists.