During the tenth series, Sharon Osbourne stated that she was only back for one series, to "go out on a high".
Also, during the first live show of series 10, Gary Barlow revealed that it would be his last series on the show.
Louis Walsh, who had also been on the show from its first series, announced his intention to quit as well, although he later backtracked and said that he "might come back" if Simon Cowell returned.
Midway throughout the live shows, Walsh said "I'm having so much fun this year, I might stay".

On 7 February 2014, Cowell, who left the UK show after series 7 to launch and judge the U.S. version, announced his return for Gary Barlow's replacement.
He said, "I'm absolutely thrilled to be returning to The X Factor UK.
It's been three years since I last judged the competition and I'm excited to find a global superstar again.
On 13 February, it was reported that Nicole Scherzinger had departed the show, On 14 February, Cowell announced that Scherzinger would not be returning by tweeting, "Nicole will always be a part of the X factor family.
Now signed to Sony as an artist.
Thank you Nicole for everything.
On 10 March, former judge Cheryl Cole announced on her Instagram that she will be returning for the eleventh series to replace Osbourne, posting an image of herself and Cowell, accompanied by the caption: "GUESS WHAT!!..
I'm baaaacccckkkkk!!!!"
On 30 May, Walsh confirmed he would be returning as a judge for his eleventh series.
On 11 June, it was confirmed that series 9 guest judge Mel B, who has also previously judged the Australian version, would join the panel as the fourth permanent judge for Scherzinger's replacement.
Following Cole's wedding to Jean-Bernard Fernandez-Versini on 7 July, it was announced by producers that she would be known throughout the series as her new married name, Cheryl Fernandez-Versini.
On 13 December 2014, it was announced that former judge Tulisa would return as a guest judge for the final due to Mel B being ill.

Dermot O'Leary confirmed his return for his eighth series as presenter of the main show on ITV.
On 3 February 2014, it was reported that Matt Richardson would not return as co-presenter on The Xtra Factor on ITV2.
This was later denied, but it was confirmed on 4 June that Richardson would not return.
On 11 June, Caroline Flack confirmed on Twitter that she will not be returning as presenter of The Xtra Factor.
The next day, it was confirmed that Sarah-Jane Crawford will be the new presenter.
Following her departure, Flack began competing as a contestant in the twelfth series of Strictly Come Dancing on BBC One.
Brian Friedman, who served as creative director from series 4-7 before returning to work on the first three live shows of series 9, returned to replace Jerry Reeve and Mark "Swany" Swanhart.

Series 11 was originally O'Leary's final series hosting The X Factor, as he announced in March 2015 his decision to exit the series to pursue other projects.
He was later replaced by Caroline Flack and Olly Murs, the latter of whom was a contestant during the competition's sixth series.
This was also originally the last series to feature Louis Walsh as a judge after 11 years, as he quit in May 2015 to return to full-time management.
It was also the only series to feature new judge Mel B. They were replaced by BBC Radio 1 presenter Nick Grimshaw and The Voice UK coach, Rita Ora.
Osbourne, Walsh, Scherzinger (who collectively replaced Cheryl, Grimshaw and Ora) and O'Leary returned to the show alongside Cowell for the 13th and 14th series, with O'Leary remaining for series 15.
During the tenth series, Sharon Osbourne stated that she was only back for one series, to "go out on a high". Also, during the first live show of series 10, Gary Barlow revealed that it would be his last series on the show. Louis Walsh, who had also been on the show from its first series, announced his intention to quit as well, although he later backtracked and said that he "might come back" if Simon Cowell returned. Midway throughout the live shows, Walsh said "I'm having so much fun this year, I might stay".
On 7 February 2014, Cowell, who left the UK show after series 7 to launch and judge the U.S. version, announced his return for Gary Barlow's replacement. He said, "I'm absolutely thrilled to be returning to The X Factor UK. It's been three years since I last judged the competition and I'm excited to find a global superstar again. On 13 February, it was reported that Nicole Scherzinger had departed the show, On 14 February, Cowell announced that Scherzinger would not be returning by tweeting, "Nicole will always be a part of the X factor family. Now signed to Sony as an artist. Thank you Nicole for everything. On 10 March, former judge Cheryl Cole announced on her Instagram that she will be returning for the eleventh series to replace Osbourne, posting an image of herself and Cowell, accompanied by the caption: "GUESS WHAT!!.. I'm baaaacccckkkkk!!!!" On 30 May, Walsh confirmed he would be returning as a judge for his eleventh series. On 11 June, it was confirmed that series 9 guest judge Mel B, who has also previously judged the Australian version, would join the panel as the fourth permanent judge for Scherzinger's replacement. Following Cole's wedding to Jean-Bernard Fernandez-Versini on 7 July, it was announced by producers that she would be known throughout the series as her new married name, Cheryl Fernandez-Versini. On 13 December 2014, it was announced that former judge Tulisa would return as a guest judge for the final due to Mel B being ill.
Dermot O'Leary confirmed his return for his eighth series as presenter of the main show on ITV. On 3 February 2014, it was reported that Matt Richardson would not return as co-presenter on The Xtra Factor on ITV2. This was later denied, but it was confirmed on 4 June that Richardson would not return. On 11 June, Caroline Flack confirmed on Twitter that she will not be returning as presenter of The Xtra Factor. The next day, it was confirmed that Sarah-Jane Crawford will be the new presenter. Following her departure, Flack began competing as a contestant in the twelfth series of Strictly Come Dancing on BBC One. Brian Friedman, who served as creative director from series 4-7 before returning to work on the first three live shows of series 9, returned to replace Jerry Reeve and Mark "Swany" Swanhart.
Series 11 was originally O'Leary's final series hosting The X Factor, as he announced in March 2015 his decision to exit the series to pursue other projects. He was later replaced by Caroline Flack and Olly Murs, the latter of whom was a contestant during the competition's sixth series. This was also originally the last series to feature Louis Walsh as a judge after 11 years, as he quit in May 2015 to return to full-time management. It was also the only series to feature new judge Mel B. They were replaced by BBC Radio 1 presenter Nick Grimshaw and The Voice UK coach, Rita Ora. Osbourne, Walsh, Scherzinger (who collectively replaced Cheryl, Grimshaw and Ora) and O'Leary returned to the show alongside Cowell for the 13th and 14th series, with O'Leary remaining for series 15.
The X Factor (British series 11)