20th Century Fox

Andy Serkis Is In 'Avengers 2,' But As Who?

As the Hulk's pet gorilla?

If you thought you knew the entire cast list of "The Avengers: Age of Ultron," think again.

As it turns out, there's at least one household name involved in Earth's mightiest sequel that's only now coming to light: Andy Serkis, the motion-capture legend responsible for Gollum in the "Lord of the Rings" series and Caesar in the upcoming "Dawn of the Planet of the Apes."

The actor confirmed in an interview with Variety that he's "playing a role" in the "Avengers" sequel, saying that he's "been working closely with Mark Ruffalo." He wouldn't reveal whether or not he's providing motion-capture for his performance, or if we'll actually see his face on-screen.

"It’s all the same to me," said Serkis. "I’ve never drawn a distinction when playing a role, whether it be live action or performance capture. Acting is acting. It’s just basically what you wear to the set that’s different."

It might not make a difference to Serkis, but it makes a difference to viewers, at least as far as trying to figure out who Serkis is playing in "Avengers: Age of Ultron." The fact that he's "working closely" with the erstwhile Doctor Bruce Banner should be the biggest tell, but even then, it's a head-scratcher. Is he providing some of the motion-capture for the Hulk? Is he playing a Tony Stark-invented robot built to keep tabs on the Green Goliath? Is he playing She-Hulk?

The possibilities are endless, but one thing's for sure: Andy Serkis involved in an "Avengers" film is a fantastic thing indeed.

"The Avengers: Age of Ultron" hits theaters on May 1, 2015.