'The Batman' director Matt Reeves explains movie's ending and surprise character (spoilers!)

Warning: This post contains big spoilers for the ending of The Batman

Riddle us this, Bat-fans: Could you spot the mystery villain that pops up at the end of Matt Reeves's box office behemoth, The Batman? Credited only as "Unseen Arkham Prisoner," this Arkham Asylum-imprisoned baddie is guaranteed to have the last laugh in the inevitable sequel.

That's right — the Joker is back to make the Dark Knight's nights a little more dark. And this time around, the Clown Prince of Crime is played by Barry Keoghan (Dunkirk, Eternals), the latest actor to inherit a role previously played on the big screen by Jack Nicholson, Heath Ledger, Jared Leto and Joaquin Phoenix.

By saving the Clown Prince of Crime for a pre-credits tease, Reeves is following in the footsteps of Christopher Nolan, who flipped over the Joker's signature playing card in the final scene of 2005's Batman Begins. And The Batman director isn't keeping his own cards close to his vest, having freely implied to press at a February post-screening Q&A that Keoghan is the Joker, no matter how he's credited.

"He's who you think he is," Reeves told a journalist who directly asked if the filmmaker would confirm the character's identity. "That's who he is. The thing about the movie is, it isn't a Batman origin story, but it is the origin story of every rogues gallery character that you come across. Selina Kyle is not yet Catwoman, and the Penguin is not yet the kingpin. And the character that you're referring to is not yet the character you're referring to, but it is in fact him."

And what would be the rogues gallery without the Joker?

Here's how the Joker factors into The Batman's universe. At the end of the film, Gotham City's Caped Crusader (Robert Pattinson) has finally caught up with the serial killer calling himself the Riddler (Paul Dano). Although he's failed to avert his enemy's master plan — blowing up Gotham's sea wall and letting the waters rush in — Batman did successfully rescue the newly-elected mayor from an assassination attempt and has emerged from the shadows to help with the rebuilding process.

Enraged that his scheme went both so right and so wrong, the Riddler proceeds to throw a snit fit in his Arkham cell. But he's overheard by another inmate who encourages him to turn his frown upside down. "Riddle me this," the helpful voice says. "The less of these you have, the more one is worth." After a beat to decode that riddle, the Riddler replies: "A friend." Cue the maniacal laughter that signals exactly who this new "friend" is.

While we never get a clear view of Keoghan in this brief scene, Reeves does hint at what the latest incarnation of the Joker might look like — including a sneering smile that more closely resembles a long scar, and a notable lack of the acid-white face we're accustomed to seeing. It's almost as dramatic a makeover as the one Colin Farrell received to play The Batman's version of the Penguin. And, funnily enough, the two Irish actors have a history together: Keoghan and Farrell both appeared in the 2017 horror film, The Killing of a Sacred Deer.

So far, fan reaction to the Joker's re-emergence has been mixed, with some psyched for Keoghan's version of the psycho, while others would rather see other members of Batman's rogues gallery get some time to shine.

The Batman is currently playing in theaters.