Have also posted this in the X-Factor section:

What's the title of the piece of music used when the contestants walk out onto the stage on The X-Factor?

I always thought it was something from the Kill Bill 1 Soundtrack.

It's called 'Battle Without Honor or Humanity' by Tomoyasu Hotei.

And yeah, it is from Kill Bill.

Thank you!

I thought it sounds like the music from the omen (damien) but maybe that was from last season...........?

I haven't watched it this year, but this music was what the judges walked out to. They had different music to the contestants.

If it's the bit of music I'm thinking of, it was also featured in Team America: World Police.