There can never be too much Batman -– which is why Brett Ratner proposes, once Christopher Nolan’s take on the Caped Crusader runs his course, that there be a few spin-off films.

“As a kid, Batman was my thing,” Ratner said. “I’m a little jealous that I didn’t get to direct it, although Nolan did a great job. But there are so many characters in the Batman series, so many characters that I love, that the opportunities for spin-offs are endless.”

Ratner thinks that the first one should be a film just about the Joker, exploring his (possible) origin as the Red Hood. “That would be really cool,” he said. But don’t we then run into the not-so-little problem of who could possibly fill Heath Ledger’s shoes?

“Heath was great,” Ratner said. “But the Joker is a great villain. That’s why Jack Nicholson and Heath Ledger had so much to work with. And I think there will be another actor who can interpret that. It would be great to see [Robert] Downey [Jr.] as the Joker, for instance.”

Ratner doesn’t want to stop there. If the opportunities for spin-offs in the Batman universe are endless, what about the rest of comic-book-dom? For the “X-Men,” for instance, Ratner is excited about the upcoming Wolverine spin-off, but he thinks one is warranted for Halle Berry’s character, Storm, as well. “That would be great,” he said. “That would be really cool.”

Spin-offs and team-ups like “The Justice League” are the way to sustain the franchises, he said, so that minor characters can be more developed.

“You’re going to be seeing superhero movies for 50 years,” he predicted. “And it’ll be exciting to see a lot of the under-the-radar franchises like ‘Iron Man’ that could be incredible on the big screen.”

Do you think anyone else can play the Joker? Should there be a “Joker” film? What should it be about? What other spin-offs would you like to see?