O'Leary in 2014
Sean Dermot Fintan O'Leary Jr.
24 May 1973
Colchester, Essex, England
Dee Koppang (m. 2012)
O'Leary's radio career began when he worked as a disc jockey at Essex Radio, but he is best known for being the presenter of The X Factor on ITV, a position he has held every year since 2007 with the exception of 2015, when he stepped down to pursue other ventures. He was then briefly replaced by Olly Murs and Caroline Flack.
O'Leary was born in Colchester, North Essex, England to parents Seán and Maria, who had moved to the United Kingdom from Ireland. He is "extremely proud" of his Irish roots and holds dual British and Irish citizenship. O'Leary attended primary school in Marks Tey and later St Benedict's Catholic College in Colchester. He admits that his relaxed attitude at school caused him to fail all but two of his GCSEs. Following that, O'Leary re-took his school leaving qualifications, allowing him to later start his A Level courses at Colchester Sixth Form College. He eventually studied for a degree in Media Studies with Politics at Middlesex University.
O'Leary started as a disc jockey at BBC Essex, based in Southend-on-Sea, before becoming a runner on the TV show Light Lunch with Mel Giedroyc and Sue Perkins and then a presenter at Channel 4 as part of the original presenting line-up of the channel's T4 strand, before moving on to present Big Brother's Little Brother (the companion show to Big Brother) on E4 from 2001 onwards. Also in 2001, O'Leary appeared on Lily Savage's Blankety Blank.
On 29 March 2007, it was announced that O'Leary would replace Kate Thornton as the new host of ITV's The X Factor for at least two series. While presenting the show, he reportedly upset Celine Dion, later saying that he "literally had to shut her up."
On 27 March 2015, O'Leary confirmed that he had quit The X Factor after 8 years to pursue other projects. Via his Twitter account, he said:
Good afternoon. After eight wonderful years on The X Factor it's time for me to move on. I'd like to thank ITV, Simon, The X Factor family and particularly the viewers, all of whom have been a big part of my life for so long. I'd like to wish the team all the best for the future, especially whoever takes over from me.
It was announced on 16 April 2015, that O'Leary's replacements would be Olly Murs and Caroline Flack, who previously co-hosted The Xtra Factor, the X Factor's behind-the-scenes companion programme, together in 2011 and 2012. 
From 2010 to 2019, O'Leary presented the National Television Awards for ITV. In 2010, 2012, 2014 and 2016, O'Leary hosted Soccer Aid on ITV, a celebrity football match in aid of the charity Unicef. In 2011, O'Leary hosted the Saturday night entertainment show The Marriage Ref on ITV. In September 2013, O'Leary hosted BRITs Icon: Elton John, a one-off music celebration for ITV.
In 2013, O'Leary presented the ITV campaign From the Heart, which encouraged viewers to consider organ donation. In January 2014, O'Leary filled in for Phillip Schofield for a week when he guest presented This Morning opposite Holly Willoughby.
On 27 November 2007, it was announced that Big Brother: Celebrity Hijack was to be O'Leary's last series of Big Brother, and that he would not return in summer 2008. After seven years, he made his final Big Brother appearance on 28 January 2008.
In March 2007, O'Leary signed a year-long contract with Channel 4 to appear on Hollyoaks. However, this was shortened after a series of disputes on set. Jim Rowe, a series writer at the time, said, "He couldn't follow even the simplest commands. It goes to show how vastly different presenting is to acting". O'Leary hasn't acted since. In 2009, O'Leary presented an episode of The Paul O'Grady Show, standing in for Paul O'Grady.
O'Leary was a presenter for Comic Relief in 2005, 2011 and 2013. He also presented Sport Relief in 2012. In August 2006, O'Leary signed a deal to present the game show 1 vs. 100, which aired on Saturday nights on BBC One in combination with The National Lottery Draws.
In March 2010, O'Leary hosted a spin-off edition of the BBC One show Question Time aimed at first time voters, which aired on BBC Three. He also presented Dermot Meets..., a series which saw him interview the likes of David Cameron, Gordon Brown, and Nick Clegg.
In 2016, O'Leary presented the BBC One Saturday night game show The Getaway Car. The series was filmed in November 2015 and began airing in January 2016. He has also guest-presented two episodes of The One Show with Alex Jones.
O'Leary joined London's indie rock station XFM in 2001, firstly presenting weekday mid-mornings from 10 am to 1 pm, before moving to a Saturday evening show in mid-2002, where he remained until late 2003.
O'Leary joined BBC Radio 2 in September 2004, presenting a Saturday afternoon show titled Dermot's Saturday Club, which ran from 2 pm to 4 pm. Following a number of changes to the length and timing of O'Leary's programme, due in part to the arrival of Chris Evans to Radio 2 and his role as presenter of The X Factor, his show was broadcast between 3 pm and 6 pm from April 2009 until its end on 21 January 2017. It focused on new music and had featured live sessions from the likes of Oasis, Supergrass, the Raconteurs, Massive Attack, Kasabian, the Guillemots, Beck, Lily Allen, Foo Fighters, Bloc Party, and Kate Nash. O'Leary also hosted Radio 2's coverage of the Brit Awards and South by Southwest. He won Sony Gold Awards for Music Programme of the Year in 2008, 2010, and 2013..
O'Leary supports Arsenal, Celtic and London Irish RUFC. He can be heard on the 'Footballistically Arsenal' podcast with his friends and fellow Arsenal fans Dan Baldwin and Boyd Hilton; on the show, it was mentioned that he owns shares in the club. He supports Wexford GAA in Gaelic games, having attended matches in the past. During a studio guest appearance on Fantasy Football Euro 2004, O'Leary spoke of his support for the Republic of Ireland football team and Ireland Rugby Union team.
On 19 November 2011 during an episode of The Xtra Factor, it was announced that O'Leary was engaged to his long-term girlfriend Dee Koppang. They married at St Mary's Church, Chiddingstone, Kent on 14 September 2012, arriving at the church in a Mercedes-Benz Pagoda. With reference to starting a family, O'Leary has stated that he would like to have children, but that his career was "hectic."
O'Leary has campaigned on behalf of Make Poverty History, and has visited Sierra Leone with CAFOD accompanied by his father. He is also a patron of the male cancer awareness campaign Everyman. In 2003, he played in a charity match for the Colchester Gladiators as a punt returner, helping to raise £2,500 for the Barnardo's children's fund.
On 7 March 2014, along with Jeremy Kyle, Bill Bailey, John Prescott, Richard Osman, Rizzle Kicks, Louis Smith, Levi Roots, and Ricky Wilson, O'Leary went commando for charity to raise awareness of testicular cancer. The promo was released on 24 February 2014.
|1999||The Dog's Balearics||Presenter|
|2002–2003||Re:covered||BBC Choice, BBC Three||Presenter|
|2000, 2008, 2009||Never Mind the Buzzcocks||BBC One||Guest team captain/Guest presenter||3 episodes|
|2001–2008||Big Brother's Little Brother||Channel 4, E4||Presenter|
|2003||Teen Big Brother: The Experiment||Presenter|
|2004||Shattered||Channel 4||Presenter||7 episodes|
|2005, 2011, 2013||Comic Relief||BBC One||Co-presenter||3 episodes|
|2006||Morning Glory||Channel 4||Presenter|
|2006–2007||1 vs. 100||BBC One||Presenter||2 series (16 episodes)|
|2007–2014, 2016–present||The X Factor||ITV||Presenter||10 series (306+ episodes)|
|2008||Big Brother: Celebrity Hijack||E4, Channel 4||Presenter|
|2009||The Paul O'Grady Show||Channel 4||Stand-in presenter||1 episode|
|2010—present||Soccer Aid||ITV||Co-presenter||4 episodes|
|2010||Question Time: First Time Voters||BBC One||Presenter||One-off episode|
|Dermot Meets...||Presenter||1 series (4 episodes)|
|2010–2019||The National Television Awards||ITV||Presenter||10 ceremonies|
|2011||Live from the Royal Wedding||BBC One||Presenter||One-off episode|
|The Marriage Ref||ITV||Presenter||1 series (7 episodes)|
|2012||Sport Relief||BBC One||Co-presenter||1 episode|
|2013||From the Heart||ITV||Presenter||One-off episode|
|BRITs Icon: Elton John||Presenter||One-off episode|
|2014||This Morning||Stand-in Co-presenter||4 episodes|
|Live From Space||Channel 4||Presenter||3 episodes|
|2015||Children in Need||BBC One||Co-presenter||Replaced Sir Terry Wogan|
|2016||The Getaway Car||Presenter||1 series (12 episodes)|
|The One Show||Guest presenter||2 episodes|
|2017||BRIT Awards||ITV||Co-presenter||37th event|
|The Nightly Show||Guest presenter||9 episodes|
|2018||The Royal Wedding of Prince Harry and Meghan Markle||BBC One||Commentator||2 episodes|
|2019||Icons: The Greatest Person of the 20th Century||BBC Two||Category presenter ("Advocate")||2 episodes, explorers category and live final|
|2019–present||Small Fortune||ITV||Presenter||1 series|
|2019||The X Factor: Celebrity||ITV||Presenter||1 series|
|2019||The X Factor: All Stars||ITV||Presenter||1 series|
|2002–2003||Saturday evenings||Show called The Weekender|
|2004–2005||BBC Radio 2||Saturdays 2 – 4 pm||Show called Dermot's Saturday Club|
|2005–2006||Saturdays 5 – 7 pm|
|2006–2007||Saturdays 4:30 – 6:30 pm||2 pm – 4 pm (during The X Factor months)|
|2008–2009||Saturdays 2 – 5 pm|
|2009–2017||Saturdays 3 – 6 pm|
|2017–||Saturdays 8 – 10 am||Show called Saturday Breakfast with Dermot|
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- "Team History". Colchester Gladiators American Football Club. Retrieved 21 May 2008.
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