Cowell got no shortage of attention. ABCNews.com rounded up nine of his most memorable moments in nine seasons of "American Idol." Remember these?
Cowell Calls Seacrest Sweetheart
Cowell and host Ryan Seacrest have long exchanged banter, often about each other's sexuality. In season 6, they stooped to new lows.
After contestant Chris Sligh's performance, Cowell asked fellow judge Randy Jackson a question, which Seacrest answered.
"You do the links, sweetheart. I'll do the judging," Simon said.
"Don't call me sweetheart," Seacrest shot back. "We don't have that kind of relationship. I don't want that kind of relationship..."
More words were exchanged with Cowell looking exasperated. "You've made this very uncomfortable Ryan, now," he said.
Cowell was always the epitome of cool but he broke a sweat the night Season 2 contestant Marine Josh Gracin challenged him to a push-up contest -- and he lost.
On stage, Cowell did his push-ups on his knuckles. It was an impressive show, but Gracin still beat him. More surprising, though, were the high-waisted slacks he sported that night, which Seacrest, of course, took a swipe at.
Cowell and Paula Abdul Fight, Make up
Cowell famously bickered with and ridiculed fellow judge Paula Abdul. But like a pair of siblings, they clearly cared for one another.
It wasn't so clear, though, during one heated debated during Hollywood Week on Season 2. When the two fought over which contestants to cut, Abdul called over producer Nigel Lythgoe. When Abdul tried to explain the problem, Cowell interrupted: "Don't talk about me, talk to my face."
"Simon, I don't have a problem saying anything in front of your face," Abdul said, turning to face Cowell.
"He can't stand someone," she told Lythgoe. Then, looking at Cowell, "There, I said it in front of your face."
Ultimately, Abdul couldn't save her pick, but the judges hugged and made up to the applause of the other contestants in the audience.
Cowell and Abdul's Affair
After two seasons of on-air bickering, Cowell and Abdul exchanged a wet kiss during the 2003 "Idol" season finale. Of course, it was just a skit.
In the taped sketch, the judges played footsie, drank champagne and shared strawberries and whipped cream during a romantic dinner. Cowell realized it was all a dream when he woke up -- with Jackson beside him.
Cowell's Eye Roll Causes Controversy
With one look, Cowell could make clear exactly how he felt. Take for instance, his famous eye rolls. While Season 6's Chris Richardson defended his "nasally" singing, Cowell rolled his eyes.
Unfortunately, this was just as Richardson, a Virginia native, was giving a shout-out to the students of Virginia Tech after the mass shooting that occurred there. A badly timed camera switch caught the eye roll and Cowell had some 'splaining to do.
Cowell Says Sorry to Katharine McPhee
Even Cowell knew when he had taken one of his critiques too far.
When the judge came under fire for eviscerating Season 5 runner-up Katharine McPhee's performance of "I Have Nothing," Cowell issued an unprecedented apology to McPhee.
"I want to apologize because I don't think this person got the right appraisal," Cowell said. "I watched it back and I thought we were unfair. It was a good performance."
It wouldn't be Cowell's last apology.
Cowell Apologizes to David Cook
In 2008, he apologized to Season 7's David Cook before Seacrest delivered the results of the final.