See Lady Gaga and Joaquin Phoenix's Dark Transformations in Joker: Folie à Deux First Trailer

Lady Gaga and Joaquin Phoenix used to think life was a tragedy, but now they realize it's a comedy.

The duo fully embraced their clownish delights in the first trailer for Joker: Folie à Deux, a sequel to the 2019 film Joker. In the new trailer, released at CinemaCon April 9, Joaquin reprises his role as the title character (real name Arthur Fleck), while Gaga takes on the iconic role of Harley Quinn, who in the DC comics serves as the Joker's lover and partner in crime, despite it being a toxic relationship for both of them.

Zazie Beetz is also reprising her role from the first film, costarring alongside newcomers Catherine Keener, Brendan Gleeson and Steve Coogan in undisclosed roles.

The trailer for Joker: Folie à Deux—which loosely translates from French as "madness together"—features Joaquin and Gaga locking eyes for the first time at Gotham's Arkham Asylum, where Arthur found himself at the end of the 2019 film.

"I haven't done anything with my life like you have," Harley tells Arthur, while the song "What the World Needs Now Is Love" plays to set the mood of their love story. Scenes then flash of the couple dancing under the moonlight and performing for crowds with "Joker & Harley" flashing on a theater stage behind them.

Their relationship seems to mark a big change for the Joker: Arthur explains that's he's truly "not alone anymore," yelling, "That's what we should be talking about."

The clip closes with Joaquin's Joker looking at Gaga's Harley from behind plexiglass, as she dramatically tells him, "I wanna see the real you."

Joker, directed by Todd Philips, was not only a box office hit, making $1 billion worldwide, but also a critical hit, earning 11 Oscar nominations and winning Best Actor for Joaquin and Best Achievement in Music for composter Hildur Guðnadóttir.

Fans will have to wait until the sequel's Oct. 4 release to see just what Gaga's Harley has in store for her Puddin', the Joker.

For more amazing onscreen transformations, keep reading.

Was eating, as his onscreen wife Emily Blunt joked "like, an almond every day," a bit nutty? Sure. But the Irish star really wanted to nail atomic bomb scientist J. Robert Oppenheimer's appearance. "Oppenheimer had a very distinct physicality and silhouette, which I wanted to get right," he explained to The New York Times. "I had to lose quite a bit of weight, and we worked with the costume and tailoring; he was very slim, almost emaciated, existed on martinis and cigarettes."

The actress lost almost 40 pounds to play the iconic jazz singer in the 2021 film, which earned her an Oscar nomination.

To transform the actress into her role of real life Appalachian grandmother Mamaw Vance in the 2020 film, makeup and special effects artist Matthew Mungle pulled Close's 2011 head cast from Albert Nobbs and sculpted her a new set of false ears and a false nose, according to Variety. The actress received an Oscar nomination for her role.

At the 2004 Academy Awards, the gorgeous A-lister was honored with a Best Actress win for her chilling portrayal of real-life serial killer Aileen Wuornos. 

The British actor packed on more than 40 pounds for his Oscar-nominated performance as a beer-bellied con artist in 2013's American Hustle. He put on the same amount to play former U.S. Vice President Dick Cheney in the 2018 movie Vice, which also earned him an Oscar nomination. The star dropped 70 pounds for the 2019 movie Ford v Ferrari, in which he plays slender race car driver Ken Miles. For the 2011 film The Fighter, which earned him his first Oscar, he lost about 30 pounds while gaining muscle.

The actor lost 52 pounds to play the deeply disturbed Arthur Fleck, the man who would become Batman's adversary.

It took three hours (and an infamously large prosthetic nose) for makeup artists to render the Best Actress winner completely unrecognizable for the 2002 drama. 

The actor shed 35 pounds and shaved his head to play an HIV-stricken attorney suing his former firm for wrongful termination. Hanks took home Best Actor at the 1994 Oscars, and made a similar transformation for his Oscar-nominated performance in 2000's Cast Away. 

The actress, who famously gained a reported 17 pounds to play the title role in Bridget Jones's Diary, did not have to change her physique to transform into Judy Garland for the 2019 film Judy, for which she won her first Oscar. You can thank the makeup and costume department for her transformation.

"Renée was extremely emotionally and artistically involved in Judy, the movie's costume designer, Jany Temime, who also worked on the Harry Potter films, told Vulture. "It was her film. I think she really got into Judy's skin."

Zellweger told the outlet, "Jany fit the costumes to Judy's posture. So the dresses didn't fit me unless I stood like I was supposed to stand. The zipper wouldn't go up."

Quite a departure from Robbie's sultry character in The Wolf of Wall Street, several prosthetics, braces and wigs helped the Best Actress nominee bring the disgraced figure skater's career-ending scandal to life in the 2017 flick. 

The Academy recognized McConaughey's extreme commitment to playing an HIV/AIDS stricken electrician with a Best Actor win during the 2014 ceremony. 

The late actor received a posthumous Oscar in 2008 for his chilling and mesmerizing performance as The Joker in the second film in Christopher Nolan's Batman trilogy. His look as the iconic villain differed greatly from those previously seen on past actors onscreen.

"What would it be if this guy slept in his makeup, this psychopath?" makeup artist John Caglione Jr. told IGN. "If he didn't spruce up his makeup for two or three weeks? He never changes his clothes It's those kinds of organic details that really helped."

He continued, "You think of a clown's makeup and for the most part, they're pretty detailed with sharp lines. But this had to be the opposite of that."

The two-time Oscar winner dramatically altered her appearance to play real-life transgender man Brandon Teena in the 1999 drama, and then again in Clint Eastwood's 2004 Best Picture winner.

In order to play British prime minister Winston Churchill, the 2018 Best Actor nominee spent upwards of four hours in the makeup chair every day and wore a "Victorian corset" style bodysuit. 

Before taking home Best Actress at the 2011 Oscars, the petite actress shed 20 pounds and trained up to 16 hours a day for her role as a mentally ill ballerina. 

Ever the chameleon, the 2014 Best Supporting Actor winner prepared to play a HIV-positive transgender woman by losing 40 pounds and only staying in character on set. 

"I had done similar things with weight, but this was different," Leto told E! News in 2013. "I think the role demanded that commitment…It was about how does that effect how I walk, how I talked, who I am, how I feel. You know, you feel very fragile and delicate and unsafe."

The Best Actress winner gained 15 pounds of muscle to play a mother who escapes years of captivity with her 5-year-old son (Jacob Tremblay) in the 2015 film. Larson said she even limited her exposure to the outside world, restricted nutrients like Vitamin D and tailored her eating habits to better grasp what her character experienced. 

At the 2012 Academy Awards, the typically fresh-faced starlet was honored with a Best Actress nomination for her performance in the thriller. Mara went as far as to pierce multiple body parts, bleach her eyebrows and chop her hair to transform into Lisbeth Salander.