Howard Stern told Jimmy Fallon on The Tonight Show he regretted his interview with late comedian and actor Robin Williams.

Stern was present on Wednesday to promote his first book in over 20 years titled Howard Stern Comes Again. The radio personality recalled some of his most interesting interviews and said that his chat with Williams was one of his biggest regrets.

"Early on in my career, I was so crazy. I couldn't allow anybody to shine in an interview," Stern said before describing his interview with Williams.

"I couldn't allow him to talk and I was so caught up in being outrageous that right away I just started hammering him with questions about his nanny and that he married his nanny. And he got very insulted," Stern continued.

"As I went through psychotherapy and I started thinking about people, I could only think about Robin Williams and how it went so wrong," he said before mentioning how years later he wanted to call Williams to apologize only to find out that he had died that same day.

Williams died by suicide in August 2014.

Stern, who referred to his book as a celebration of some of his best interviews, mentioned how Fallon is featured in the book discussing how he messed with President Donald Trump's hair in the lead up to the 2016 presidential election. The infamous moment critics have said helped Trump get elected.

"I thought the bit was fantastic," Stern said, defending Fallon. "It was absolutely absurd this whole idea that you humanized him. I didn't buy into it and I thought the bit was solid."