Forget all aboutBatman vs. Supermanimmediately, because the only superhero-powered clash of the titans worth thinking about anymore isPoppins vs. Poppins: Supercalifragilisticexpiali-Justice.EWconfirmed that Oscar-winnerJulie Andrewshas an until-now-secret role inAquaman.DirectorJames Wan’s underwater DC superhero epic just happens to be set to go head-to-head at the December box office withRob Marshall’sMary Poppins Returns, starringEmily Bluntin the magical umbrella-wielding title role made famous by Andrews in her feature film debut.
ForAquaman, Andrews will lend her voice to the character Karathen, an aquatic creature created entirely for the film who is “key” to Arthur Curry’s (Jason Momoa) orange-and-green mission to bring peace between the surface world and his native Atlantis.

“We wanted Karathen to have the voice of a classic British actress, albeit somewhat digitally altered,”AquamanproducerPeter Safransaid. “And when we found out Julie was interested and available and excited to do it, casting her was a no-brainer…Who knew thatAquamanwould have the real Mary Poppins this Christmas?”
Aquaman—which also starsAmber Heard,Nicole Kidman,Patrick Wilson,Yahya Abdul-Mateen II,andWillem Dafoe—surfs into theaters on December 21.Mary Poppins Returnswill beat it there by a few days on December 19. May the best Poppins win.

Here is the official synopsis for James Wan’sAquaman:
From Warner Bros. Pictures and director James Wan comes an action-packed adventure that spans the vast, visually breathtaking underwater world of the seven seas, “Aquaman,” starring Jason Momoa in the title role. The film reveals the origin story of half-human, half-Atlantean Arthur Curry and takes him on the journey of his lifetime—one that will not only force him to face who he really is, but to discover if he is worthy of who he was born to be…a king.
