Many of Justice League‘s key roles were filled even before the film entered pre-production, because many of those characters were needed for Man of Steel and Batman v Superman: Dawn of Justice. Still more of them were cast back in the spring, as shooting got underway. But there’s been one glaring omission this whole time.

Though we’ve known for months that the villain of Justice League would be Steppenwolf, we’re just now learning who’ll play the part. Irish actor Ciarán Hinds has joined Justice League to portray Steppenwolf through the power of mo-cap. Hinds is probably best known right now in the U.S. for playing Mance Rayder in HBO’s Game of Thrones.

TheWrap reports Hinds recently wrapped his motion capture role on Justice League. It’s unclear when exactly Hinds was hired. When Peter visited the Justice League set in June, producer Deborah Snyder said they hadn’t quite nailed down an actor for the Steppenwolf part. “We’re not completely closed,” she told him. “So I’m sorry, I can’t share that. We’re close.” Although filming was well underway, since Steppenwolf is a motion capture part, they didn’t need an actor for the role at that point.

Initially, most fans had assumed Darkseid would be the big bad of Justice League. But days after Batman v Superman hit theaters, Warner Bros. shared a deleted scene that offered our first peek at Steppenwolf. Not that many people knew it at the time — the mysterious alien-looking figure had a lot of fans scratching their heads, since he didn’t much resemble the Steppenwolf of the comics. It took a few more weeks for word of his identity to get around.

The deleted scene is set at the end of Batman v Superman. In it, a SWAT team moves in on the Kryptonian ship to apprehend Lex Luthor (Jesse Eisenberg), and sees a strange figure — whom we now know to be Steppenwolf — levitating a trio of mother boxes before disintegrating. As you can see above, the New 52 comics version of Steppenwolf looks basically like a human in weird armor, and not at all like the bizarre alien in Batman v Superman. You can revisit that scene below:

Those Mother Boxes apparently play a big role in Justice League. Peter reported that there are three Mother Boxes — an Atlantean one, an Amazonian one, and a human one. “These Mother Boxes are best when they work in threes,” teased producer Charles Roven. “The Amazonians and the Old Gods came together and decided that based on an event that happened, these Mother Boxes were going to be placed in the care of the Amazonians, the Mankind and the Atlanteans.”

The Mother Boxes are Apokoliptian technology, which is probably where Steppenwolf comes in. In the comics, he’s the military leader of the planet Apokolips, which is ruled by Darkseid. He leads an invasion of Earth, bringing Darkseid’s parademons with him. Parademons, of course, are those winged creatures we saw in the Knightmare action sequence of Batman v Superman.

Directed by Zack Snyder, Justice League opens November 17, 2017.