L.A. Reid is a hit maker. He is responsible for a lot of huge careers – the names Pink, Justin Bieber, Rihanna come to mind. That's why he is an 'X Factor' judge. However, he has one massive regret in his career and that is letting Lady Gaga go. That's right. Reid had signed her when he was the head honcho at Island Def Jam and then swiftly dropped her.

While chatting with Ellen Degeneres on her namesake show, Reid recalled Gaga playing piano while wearing white go-go boots at his office. He told her she would change music, and he was right.

At the time, though, he had a change of heart.

"Two months later, I forgot that I said that," Reid recalled. After the A&R guy that she was working with played the music for Reid, he said, "This is disgusting. I dropped her and I dropped him. It was the biggest mistake I ever made."

Even so, Reid said Ma Monster is better off where she is, since the right label fit is a combo of many factors. He joked, "It makes me feel better to think she wouldn't have been as successful with me."

If that helps him sleep at night…