When Todd Phillips first announced a sequel to his billion-dollar gritty character study, the internet collectively lost its mind. People weren't just curious about the story; they were obsessed with the cast of Joker: Folie à Deux. It’s a weird mix. Honestly, on paper, it shouldn’t work. You have a method-acting titan returning to his most iconic role, paired with a pop star who has reinvented herself as a dramatic powerhouse, all wrapped up in a musical psychological thriller.
It's bold. It’s risky.
The movie basically centers on the "madness of two." That’s what the title means, after all. But while everyone is looking at the big names on the poster, the supporting players are actually the ones who ground this fever dream in some version of reality.
The Return of Joaquin Phoenix as Arthur Fleck
You can’t talk about the cast of Joker: Folie à Deux without starting with the man who started it all. Joaquin Phoenix is back. He’s thinner, paler, and somehow even more haunting than he was in 2019.
Phoenix didn’t actually want to do a sequel at first. He’s famously allergic to franchises. But reports from the set and interviews with Phillips suggest that Phoenix had dreams about Arthur Fleck performing on stage. That was the spark. In this film, Arthur is no longer just a failing stand-up comedian; he’s a prisoner at Arkham State Hospital, waiting for the trial of the century.
His performance isn't just a repeat of the first film. It’s more internal. He’s playing a man who is caught between two identities—the broken Arthur and the theatrical Joker.
Lady Gaga as Harleen "Lee" Quinzel
This is where things get controversial. Or at least, interesting. Lady Gaga joins the cast of Joker: Folie à Deux not as the Harley Quinn we know from the comics or the Margot Robbie films, but as "Lee."
Forget the acid vat. Forget the "Daddy’s Lil Monster" shirts.
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Gaga’s version of the character is a fellow patient at Arkham. She’s an arsonist. She’s obsessed with the Joker persona, not necessarily the man behind it. The chemistry between Phoenix and Gaga is the engine of the entire movie. If you’ve seen the clips of them dancing on the iconic Joker stairs in the Bronx, you know they aren't going for "superhero movie" vibes. They’re going for A Star Is Born meets Natural Born Killers.
Gaga reportedly stayed in character throughout the shoot, insisting that people call her Lee even when the cameras weren't rolling. It sounds exhausting. But for a movie that relies so heavily on a shared delusion, that kind of commitment is probably the only way to make the musical numbers feel like they belong in a dirty, depressed Gotham.
The Supporting Players and Familiar Faces
While the leads get the spotlight, the rest of the cast of Joker: Folie à Deux fills in the gaps of Arthur’s crumbling world.
Zazie Beetz is Back (Sort Of)
Remember Sophie Dumond? The neighbor Arthur imagined a whole relationship with? Zazie Beetz returns, which is a bit of a shocker considering how the first movie ended. Her presence raises a lot of questions about what is real and what is just another "folie" in Arthur's head. She represents the "real world" that Arthur left behind, and her testimony during the trial sections of the film provides a gut-punch of reality.
Brendan Gleeson as the Arkham Guard
Brendan Gleeson is a legend. Period. In this film, he plays Jackie Sullivan, a lead guard at Arkham who has a complicated, almost transactional relationship with Arthur. He’s not a cartoonish villain. He’s a guy doing a job in a broken system. Gleeson brings a weight to the movie that prevents it from floating off into total musical fantasy.
Catherine Keener and Harry Lawtey
Catherine Keener joins as Maryanne Stewart, Arthur’s lawyer. She’s trying to argue that Arthur has a dissociative identity disorder—basically trying to save him from the death penalty by blaming the "Joker" persona.
Then there’s Harry Lawtey. Most people recognize him from the HBO show Industry. Here, he plays Harvey Dent. But don't expect Two-Face. At this point in the timeline, he’s just a young, ambitious Assistant District Attorney looking to make a name for himself by putting Arthur Fleck away for good.
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Why the Musical Element Changed the Cast's Approach
You've probably heard that this isn't a "traditional" musical. The cast of Joker: Folie à Deux had to approach the singing as an extension of their mental states.
Hildur Guðnadóttir, the composer who won an Oscar for the first film, returned to weave these songs into the score. The actors aren't singing like Broadway stars. They’re singing like people who are losing their minds. It’s raw. It’s often off-key on purpose.
Phoenix and Gaga performed much of the music live on set with a piano player off-camera. This meant the rhythm of the scenes could change on the fly. It gave the actors an incredible amount of freedom, but it also meant the supporting cast had to be incredibly disciplined to stay in the moment while the leads were essentially "hallucinating" through song.
The Trial of the Century: Gotham’s New Reality
A huge chunk of the movie takes place in a courtroom. This shifts the energy of the cast of Joker: Folie à Deux from the isolated, claustrophobic hallways of Arkham to a public stage.
- Steve Coogan shows up as a sensationalist TV host interviewing Arthur.
- Ken Leung and Bill Smitrovich appear in roles that flesh out the legal and psychiatric bureaucracy of Gotham.
- The background extras—the "Joker sycophants"—act as a character themselves, representing the growing unrest in the city.
This isn't just a trial about murder. It's a trial about whether the Joker is a symbol or a symptom. The actors playing the jurors and the gallery have to react to Arthur's outbursts, which often involve him breaking into song or adopting a Southern drawl. It’s a circus.
Fact-Checking the Rumors
There was a lot of nonsense floating around Reddit during production. No, Tom Hardy doesn't make a cameo as Bane. No, this isn't secretly a prequel to the Robert Pattinson Batman movie.
The cast of Joker: Folie à Deux is strictly contained within its own universe. Todd Phillips has been very vocal about the fact that this is a standalone story. It’s a character study first, and a "comic book movie" a distant second.
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What This Means for the Audience
If you're going into this expecting a high-octane ensemble piece like The Avengers, you're going to be disappointed. The cast of Joker: Folie à Deux is small and focused. It’s designed to make you feel as trapped as Arthur is.
The nuance in the performances is what carries the film. Phoenix’s physicality—the way his ribs stick out, the way he drags his feet—is a performance in itself. Gaga’s eyes tell a story of someone who is bored with the world and finds the only thing worth living for in a man who thinks he’s a clown.
Actionable Takeaways for Moviegoers
If you want to truly appreciate what the performers are doing here, keep a few things in mind before you watch:
- Watch the first film again. Pay close attention to Zazie Beetz’s scenes. It will make her appearance in the sequel much more impactful.
- Listen to the lyrics. The songs aren't just filler. They are "cover" versions of standards like "That's Entertainment" and "For Once in My Life." The way the cast interprets these lyrics tells you exactly what’s happening in their subconscious.
- Look at the background. The production design of Arkham and the courtroom is meant to contrast the colorful, vibrant musical sequences. The actors have to bridge that gap.
- Forget the comics. This version of Harvey Dent and Harley Quinn is unique to this director. Judging them based on the 1990s animated series will only confuse you.
The cast of Joker: Folie à Deux took a massive swing. Whether it lands for you depends on how much you’re willing to go along with Arthur’s delusion. It’s a movie about the stories we tell ourselves to survive, and how dangerous it is when someone else starts believing those stories too.
To get the most out of the experience, focus on the shifts in Joaquin Phoenix's voice. He uses several different tones depending on whether he’s talking to his lawyer, the guards, or Lee. It’s a masterclass in vocal characterization that anchors the entire chaotic production.
Next Steps for the Reader:
Check out the official soundtrack or the "behind the scenes" featurettes that focus on the live vocal recordings. Understanding the technical difficulty of singing live while maintaining a dramatic performance will give you a much deeper appreciation for what Gaga and Phoenix achieved on screen.