'Justice League' release date, cast news, spoilers: Mera to appear in film alongside Aquaman; Steppenwolf to be the antagonist in the movie

It has been confirmed that Mera, portrayed by Amber Heard, will be seen alongside Aquaman (Jason Momoa) in "Justice League." Meanwhile, Batman (Ben Affleck) and his new allies will be facing the villain Steppenwolf, portrayed by "Game of Thrones" star Ciaran Hinds.

Directed by Zack Snyder, "Justice League" is set to premiere on Nov. 17 featuring Batman and Wonder Woman (Gal Gadot) preparing to face a bigger evil than they've seen before.

The synopsis reads: "Together, Batman and Wonder Woman work quickly to find and recruit a team of meta-humans to stand against this newly awakened threat. But despite the formation of this unprecedented league of heroes – Batman, Wonder Woman, Aquaman, Cyborg (Ray Fisher) and The Flash (Ezra Miller) – it may already be too late to save the planet from an assault of catastrophic proportions."

Aside from the heroes that form "Justice League," Chief Creative Officer and President of DC Entertainment Geoff Johns revealed that Queen Mera will be appearing as well.

Johns' Twitter post reads, "@ZackSnyder's @justiceleaguewb Featuring among many things the first ever live action Mera!!!"

Johns even hinted that Mera might even play a big part in the "Justice League" film.

Meanwhile, The Wrap confirmed that the Justice League will be facing the comic villain Steppenwolf, who will be played by "Game of Thrones" star Ciaran Hinds.

Steppenwolf is known as an immortal alien with superhuman strength and speed. The villain had already appeared in a deleted scene from "Batman v Superman: Dawn of Justice."

The villain was in communication with Lex Luthor (Jesse Eisenberg) while he was in a Kryptonian ship. But moments later, the SWAT team arrived to take away Luthor, and Steppenwolf disappeared.

Steppenwolf is said to be after three mother boxes known as MacGuffins in "Justice League."

"Justice League" premieres on Nov. 17.