SPOILER ALERT: Do not read if you have not yet watched “The Batman.”

Although Barry Keoghan is an established character actor who has put in memorable performances in several high-profile movies, such as “Dunkirk,” “Eternals” and “The Green Knight,” it’s his brief cameo at the very end of “The Batman” that could elevate him into a household name. Palling around in Arkham Asylum with The Riddler (Paul Dano), the pair have a behind-bars gab session about their criminal ideologies, which includes Keoghan’s character mentioning the word “clown” and giving a very sinister laugh. It doesn’t take the World’s Greatest Detective to figure out that this figure — although only visible in profile and referred to in the credits as “Unseen Arkham Prisoner” — will return to haunt Batman as another incarnation of the Joker.

Outside of being Batman’s most iconic foe, the role has attracted Hollywood royalty, earning Heath Ledger and Joaquin Phoenix Academy Awards for their dark performances. While the Joker typically is played by outsized A-listers, including Jack Nicholson, Jared Leto and even Mark Hamill in a fan-favorite vocal performance, Keoghan might strike moviegoers as a bit of a wildcard.

But fear not: Anyone familiar with Keoghan’s work in a disturbing 2017 indie will know he’s an inspired choice — and anyone new to his performances should check it out immediately. That film is Yorgos Lanthimos’ haunting “The Killing of a Sacred Deer,” a small-scale thriller about the Murphy family, led by “Batman” co-star Colin Farrell and Nicole Kidman, tortured by a young man named Martin (Keoghan), who enters their life through mysterious circumstances.

The film is filled with many disturbing twists, but suffice to say that Keoghan is a haunting villain, full of blank expressions and pitiless stares in even the most distressing moments. Furthermore, his views on justice and morality are resolute but slippery to both the Murphys and the audience. Martin’s DNA is so in line with the peculiar lawlessness and mystery of Ledger’s Joker that this film could practically be canon, an origin story of a supervillain in his early days. Even the small physical nuances of Keoghan’s acting — odd gestures and movements while staring, walking and even eating spaghetti — would make his performance pop off of the screen as the Joker.

As for the exact future of the character in this new “Batman” series? It’s uncertain, as director Matt Reeves recently spoke with Variety‘s Adam B. Vary about how the scene was not meant to specifically tease the sequel, but rather show the texture of Gotham’s underworld.

“I never was trying to say like, ‘Hey, guess what, here’s the Joker. Next movie!'” Reeves said. “That was never the idea. The idea was more to say, ‘Hey, look, you know what? If you think that trouble is going to go away in Gotham, you can forget it. It’s already brewing. It’s already here. And it’s already delicious.'”

Sample the “Killing of a Sacred Deer” trailer below, and watch the whole film on Netflix if you want to marvel at Keoghan’s performance.