Louis Walsh, the mastermind behind a string of hit UK artists including Irish boyband Westlife, has stormed out of the show after repeated insults from acid-tongued Cowell and fellow judge Osbourne got out of hand.
Saturday's (19NOV05) programme saw a seething Osbourne throw three glasses of water over her colleague after a snide comment about her rocker husband Ozzy.
Walsh has also been slammed by the British press for booting favourite-to-win contestant MARIA LAWSON from the show in favour of an Irish girl group who he was friends with.
He says, "I've been totally humiliated and undermined by both of them. This has caused me nothing but stress.
"The final straw was Sharon with the water and being booed by the audience - and then Simon Cowell saying I was an idiot and stupid.
"I've had enough. I'm going back to Dublin. I'm not putting up with it anymore."
Both American Idol judge Cowell and Sharon Osbourne have expressed their dismay at Walsh's decision and are pleading for him to re-think.
Cowell says, "I've known Louis for years. I know what a huge success he's been. If I offended him I apologise. We want him back."
"Osbourne adds, "I am shocked and saddened. I like and respect Louis and I hope he changes his decision."
X Factor management officials were last night (22NOV05) holding crisis talks with the 52-year-old in a bid to win him back.