"Avengers: Age of Ultron" actor Mark Ruffalo has revealed why he doesn't have a standalone "Hulk" movie yet. The 47-year-old Hollywood actor also gushed about his gigantic superhero character's major enemy.

Ruffalo recently did an interview with Collider, and the "Avengers" actor revealed the main reason why Marvel has not created a "Hulk" standalone movie yet.

"As far as a Hulk movie, a standalone Hulk movie, Marvel doesn't really have the rights to that yet," Ruffalo said. "That's still Universal's property, so there's that issue. That's a big impediment to moving forward with that. [But] I don't think that's insurmountable."

However, it appears that creating a standalone film for his superhero character will not be easy even though Marvel will acquire the rights to it. 

Speaking with Entertainment Weekly, Ruffalo said that the main issue with his character is the fact that the Hulk does not want to be there. 

"It's hard to make a movie about a guy who doesn't want to be there. And he doesn't want to do the very thing that you want him to do," he said.

Ruffalo also gushed about his character's greatest enemy saying: "I think there's a whole relationship with [Bruce] Banner and Hulk that needs to be discovered. There's a very cool thing happening: Hulk is as afraid of Banner as Banner is afraid of Hulk."

Interestingly, Ruffalo could be hiding something from fans since insiders learned that there is a big possibility of a standalone "Hulk" movie after "Avengers: Age of Ultron."

HitFix reports that in the final moments of "Age of Ultron," Ruffalo's Hulk would be stuck inside a Quin ship that is bound to end up in another destination outside of Earth. Could this be the start of the Hulk's solo adventure?