Aquaman gets shock A-list cameo: Guess which MEGASTAR has been cast in surprise role?

The Jason Momoa-fronted movie has been performing exceptionally well on pre-sales, indicating it could give DC its biggest big-screen hit since Wonder Woman. And if star power is anything to go by, you arguably can’t get much better than this surprising piece of casting news. Mary Poppins Returns may be coming out in the same month as the superhero caper, but this is the one with Julie Andrews on its cast list.

According to Entertainment Weekly, Andrews has provided the voice of Karathen; an underwater creature that plays a crucial role in Aquaman’s story.

But whether she’s working for or against him remains to be seen.

“We wanted the Karathen to have the voice of a classic British actress, albeit somewhat digitally altered,” producer Peter Safran said.

“And when we found out Julie was interested and available and excited to do it, casting her was a no-brainer.

“Who knew that Aquaman would have the real Mary Poppins this Christmas?”

Aquaman will also star Amber Heard as Mera, Willem Dafoe as Nuidis Vulko, Patrick Wilson as Orm and Nicole Kidman as Atlanna.

Dolph Lundgren, Yahya Abdul-Mateen II and Djimon Hounsou are also on board.

Momoa recently revealed that he got the role by auditioning for Batman.

“And I almost didn’t go because I was like, ‘This is bulls**t. I’m not a white guy. I ain’t playing Batman,’” he told EW.

“Even if I do, I don’t even want to. It’s like an American playing James Bond, you know? I almost didn’t do it. I thought for sure I was going to be playing [DC Comics villain] Lobo or something.

“The only people I knew they were casting for were Batman, Superman, and Wonder Woman — who the hell am I going to play?

“So in the meeting, I just played it as if Batman had died in an alley and some thug picked up his suit and put it on. I just played him as a smart ass, jaded and sarcastic.

“And that’s when Zack [Snyder] was like, ‘I have an idea…’”

Aquaman is out on December 14 in the UK.