Batman franchise producer Michael E. Uslan reveals the key advice imparted by late mentor and friend Stan Lee: every superhero needs a worthy supervillain.

“I am a subscriber to Stan Lee’s theory of supervillains,” Uslan said of the Marvel Comics visionary at Germany’s CCXP Cologne convention.

“Stan said to me, ‘Michael, the reason those superheroes who are the most long-lasting and the most popular are the ones who have had the greatest super villains.’ He said, ‘Ultimately, it is the supervillains who define the superheroes.’”

“And if you look at Batman, out of the entire world of comic books, he’s had the greatest rogues gallery of super villains in history. Unarguably the greatest supervillain in history in the form of the Joker,” Uslan continued.

“And as a comic book fanatic, the only two superheroes who come even close to Batman in terms of supervillains are Spider-Man and the Flash.”

Uslan — who collaborated with the Spider-Man and Avengers co-creator on Lee’s Just Imagine..., one of just a handful of works Lee contributed to rival DC Comics — earlier found fame and international attention when offering the first accredited course on comic books, which won him a phone call from Lee.

“My phone rings, and it’s this exuberant male voice. He goes, ‘Hi! Is this Mike Uslan?’ I go, ‘Yeah.’ He goes, ‘Hiya Mike! This is Stan Lee from Marvel Comics in New York City.’ I call this my burning bush moment,” Uslan said.

“I was talking to my god. He says, ‘Mike, everywhere I look, I’m reading about you in newspapers, I’m seeing you on television. What you’re doing is great for the entire comic book industry, how can I help you?’ And that began my adult relationship with Stan that would be a friendship that would last the rest of my life.”

Uslan at CCXP also defended the casting of Robert Pattinson in Matt Reeves’ The Batman and teased the Todd Phillips-directed Joker is “unlike any comic book movie you’ve ever seen.”