Cheryl Cole - who was given her big break on TV talent show Popstars: The Rivals - will tell the X Factor hopefuls she can sympathise because she has been in their position.
The Girls Aloud star says: "I've been there and I have been here so I know how you are all feeling, I am just excited to see what you have got. [I] think it's going to be amazing and I wish you the best of luck from the bottom of my heart."
Other guest mentors include Tinie Tempah, who teams up with Tulisa Contostavlos, Ne-Yo who accompanies Nicole Scherzinger and Sharon Osbourne who is the sidekick to Louis Walsh.
More top news
There will be a widespread frost and ice to watch out for tonight, with some bitterly cold temperatures too.
Famous faces have helped a boyfriend deliver the ultimate romantic proposal to his girlfriend of 12 years.
The Turk who shot and wounded Pope John Paul II in 1981 has laid flowers on the saint's tomb in St Peter's Basilica, the Vatican said.