The finalists were revealed in tonight's (September 30) second Judges' Houses episode, which saw the four judges reveal which acts were successful.
Nicole Scherzinger was joined by Ne-Yo in selecting her final three, and chose Rylan Clark, James Arthur and Jahmene Douglas in her Boys category.
Tulisa Contostavlos - helped by Tinie Tempah - went for Jade Ellis, Lucy Spraggan and Ella Henderson for the Girls.
Melanie Masson, Kye Sones and Carolynne Poole were chosen by Gary Barlow for the Overs, with assistance from Cheryl Cole.
Finally, Louis Walsh and Sharon Osbourne kept GMD3, MK1 and Union J in the Groups category.
Gary Barlow said of the final list of contestants: "This year we really have got the cream of the crop with our finalists and it was tough for all of us to choose our three acts. The standard of talent has gone up this year and I think it's the best ever line-up of finalists.
"The live shows will feel very different this year too as contestants can sing their own songs and play guitar - I can't wait for Saturday!"
Four acts were also revealed to be among this year's Wildcard contestants, with each judge giving one artist in their category an extra chance of making the live shows.
Christopher Maloney (Overs), Adam Burridge (Boys), Amy Mottram (Girls) and Times Red (Groups) will go up against each other in a public vote that will continue until next Saturday's live show, with the winning act performing alongside the other 12 finalists.
The X Factor continues with its first live show on Saturday, October 6 at 8pm on ITV.
Photo gallery - The X Factor final 12:
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