The wannabe is fuming after Cowell insulted him onstage and has vowed vengeance in emails to a fellow contestant, which reveal plans to stab the 42-year-old.
The threatening messages are so violent, Cowell has hired an additional bodyguard to protect him while on the X-Factor set.
Cowell says, "My bosses told me they have been shown emails threatening my life. They said one man wanted to stab me.
"It sent a chill down me. But I'm used to it."