Simon Cowell has been hailed as nothing like his "TV's Mr Nasty" persona.

The music mogul, 65, built the reputation with his blunt feedback to acts on shows including The X Factor, but fans who met him by chance in Los Angeles has now praised him for being "kind" and "genuine".

Fan John Jilwan wrote on Q A site Quora: "I ran into him by chance once in Los Angeles. He's nothing like how he appears on television. In fact, he was one of the kindest, most genuine people I've stumbled upon. While our conversation wasn't long, he was very friendly and seemed very down to earth and upbeat." John added that Simon was "a really good guy" and "not at all like the overly critical jerk he appears to be on television."

Another admirer, Joe Deilbirt, recalled an encounter with Simon at a hotel bar.

He said: "Myself and a few other guys ran into him at a hotel bar and grill once at a hotel we were all staying at and he bought us all a few rounds of drinks as we all talked and had laughs about some of the good, and not so good, American Idol contestants over the years."

Joe also described Simon as "a humble man and nothing like his TV character".

Along with The X Factor, Simon has built his career on shows including Britain's Got Talent and American Idol.

He is also the producer behind the global Got Talent franchise and the founder of Syco Entertainment, the label that helped launch One Direction and other chart-topping acts.

The fans' stories emerged as Simon shared a rare set of personal photographs from backstage at America's Got Talent.

He posted images on Instagram with his son Eric, 11, and his fiancée Lauren Silverman, 48, along with their pet chihuahua Daisy.

Simon wrote alongside the snaps; "Everyone's happy."

They showed him in a black T-shirt and Eric in a bright blue jersey with the show's logo.

This season of America's Got Talent is being judged by Simon, Howie Mandel, Mel B and Sofia Vergara. Three more acts - Bay Melnick Virgolino, a ten-year-old guitarist, the Leo High School Choir, and the dance troupe Unreal - advanced to the series' September semi-finals, joining previous qualifiers Jourdan Blue, LightWire and Sirca Marea.

Singer Mama Duke has already secured a place in the final after receiving Mel B's Golden Buzzer.