LOS ANGELES — Are the major Hollywood studios with rights to various Marvel Comics characters talking about a massive movie crossover? Though it may never happen, it would seem they've at least been noodling the idea — this according to none other than Stan Lee.

The 91-year-old co-creator of Iron Man, Captain America, Spider-Man, Thor and just about every major Marvel character did a Q&A and book signing on Saturday with Roy Thomas (Lee's first successor as editor-in-chief at Marvel) and filmmaker Kevin Smith at the Hammer Museum to mark Marvel's 75th anniversary.

At about the 53-minute mark (see video below), an audience member dressed in Captain America gear asked Lee whether we'll ever see Spider-Man, the X-Men and the Avengers — owned by Sony, Fox and Disney, respectively — come together onscreen.

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"It's something that Marvel is very concerned about," Lee replied. "It's very difficult to bring 'em all together because these characters are so successful and make so much money that the studios that have the rights don't want to let them go. So that's something that all the lawyers and all the production companies have to work out. Whether they get it worked out, I don't know."

Marvel Studios president Kevin Feige has addressed this issue on multiple occasions — he's always asked — including during a Q&A after an October event announcing Disney/Marvel's Phase Three cinematic plans. But he's always deftly dodged the particulars, expressing the will to someday cross the cinematic streams without letting on that any tangible discussions have taken place.

But was Lee hinting that studio suits have actually taken meetings? And/or that those talks have resulted in an expressed mutual interest, and now it's down to formalities? Because there's no one in the world who doesn't see the financial potential there, Lee being no exception.

"It is a shame that [Disney]- Marvel can't distribute every one of them. Because then we could put them all together ... in a movie that would make a hundred trillion dollars!"

Lee also talked a bit about his many cameos in Marvel movies, and let slip that he'll appear in the fourth episode of Agent Carter, which debuts Jan. 6. And his best cameo is yet to come, he said, in Avengers: Age of Ultron.

But let's face it: The only cameo we really want to see is when he walks into a room where Peter Parker, the Avengers, the Fantastic Four and the X-Men are popping the cork on that hundred-trillion-dollar movie franchise.