The Baby One More Time singer was on the panel of the US version of the show alongside L.A. Reid, Demi Lovato and Simon Cowell in 2012.
The former X Factor co-host hailed his friend as “a fantastic presenter, and someone who was just natural on TV”.
Lucy has spoken for the first time about being assaulted by a hotel porter, leading to her leaving the competition early.
The former Bath player was last seen in Barcelona in October.
The X Factor boss weighs in on his former Saturday night TV rival.
His concerned family and friends are appealing for information after he was last seen at a pub in Spain on 29 October.
"I can’t wait to get my dancing shoes on!"
Simon Cowell And Spice Girls Pay Tribute Following Death Of X Factor Star Tom Mann's Fiancée, Dani Hampson
The professional dancer died on what would have been her wedding day to the former Stereo Kicks star.
Tom said that what was "supposed to be the happiest day" of their lives "ended in irreversible heartbreak".
Although he was considered a "novelty act" during his series, Rylan has become one of the most successful X Factor acts ever.
About X Factor
Since its launch in 2004, 'The X Factor' has become the biggest talent show in the UK. The brainchild of Simon Cowell, the series has launched the careers of some of the biggest names in music - One Direction, Olly Murs, Leona Lewis, Ella Henderson, Alexandra Burke and Fleur East to name just a few. This year's judges are made up of Simon, Louis Walsh, Sharon Osbourne and Nicole Scherzinger. Previous panellists include Cheryl Fernandez-Versini, Gary Barlow, Tulisa Contostavlos, Kelly Rowland, Dannii Minogue, Mel B, Rita Ora and Nick Grimshaw. Host Dermot O'Leary quit the show in 2015 to be replaced by Caroline Flack and Olly Murs, only to announce his return a year later. Kate Thornton was show's original presenter, hosting the first three series. For this year's series, ITV2 spin-off show 'Xtra Factor' has been axed. On this page, you will find the latest news, gossip, pictures and video from the ITV show, as the contestants go through auditions, Bootcamp, the Six Chair Challenge, Judges Houses and the Live Shows.