'Avengers: Doomsday' Reportedly Adds Beloved MCU Anti-Hero to Stacked Cast

Sure, it’s fun to envision Robert Downey Jr.’s Doctor Doom going toe-to-toe with Ryan Reynolds’ Merc with a Mouth on the big screen in the Marvel Cinematic Universe. Heck, maybe that’s how Deadpool/Wade Wilson (Reynolds) ended up crying in Thor’s (Chris Hemsworth) arms during 2024’s blockbuster hit, Deadpool & Wolverine. Well, MCU fans can start celebrating, and the censors can start contemplating if the film will need an R rating, because sources have revealed that Reynolds’ foul-mouthed anti-hero has reportedly joined the cast of Avengers: Doomsday.

The news comes courtesy of The Hollywood Reporter’s Heat Vision, which is the publication's "voice in the geek sphere" when it comes to "all things comics, sci-fi and horror." According to the unnamed sources, Deadpool is going to show up in 2026’s highly anticipated Avengers: Doomsday, but the report also cautions fans not to expect the Merc with a Mouth to join the superhero squad in the fifth Avengers film.

Heat Vision’s sources appear to corroborate Reynolds' social media post from earlier (Monday, Aug. 11), which many considered to be a tease by the actor hinting at his involvement in Avengers: Doomsday. Reynolds simply posted an image of the Avengers’ symbol with a graffiti-red letter "A" scrawled over the superhero team’s emblem in what appears to be an act of protest.

One of the things Deadpool wanted more than anything else at the beginning of Deadpool & Wolverine was to join the famous squad, but Happy Hogan (Jon Favreau) crushed those dreams rather quickly. However, it seems Marvel fans’ dreams have come true as Reynolds reportedly joins the already star-studded cast.

Fans Are Dying to See Deadpool in 'Avengers: Doomsday'

Ryan Reynolds' Deadpool tease in Avengers: Doomsday hadn’t even been confirmed when the actor dropped the now iconic Instagram post online. However, that didn’t stop the fans from going wild in response to the news that the Merc with a Mouth might be joining the sequel. One social media user, @franelleart, wrote in response to the tease in the post’s comments:

"RYAAANNNNNNNN!!!! LFG???!!! 😍😍😍😍"

Another of Reynolds’ followers wrote a response that suggests the die-hard fan might not be able to handle Deadpool’s presence in Avengers: Doomsday, or that they doubt the foul-mouthed Mutant will actually show up in the sequel. @reynoldsfanarmy wrote:

"Ryan, my therapist will be hearing about this 😭"

@louise_rrfan added:

"Could it actually be??? 🤞🤞🤞🤞🤞"

Doomsday is already stacked with heavy-hitting A-list actors, even without Reynolds’ Deadpool. Nonetheless, he will be joining the likes of not only the aforementioned Robert Downey Jr. and Chris Hemsworth. Additionally, Reynolds will be sharing the spotlight with Marvel mainstays Sir Patrick Stewart, Paul Rudd, and Tom Hiddleston.

Plus, don’t count out appearances by Mark Ruffalo’s Hulk or Tom Holland’s beloved webslinger, because they will cross paths next summer in Spider-Man: Brand New Day. Then, later that year, look for Deadpool in Avengers: Doomsday when the film hits theaters on Dec. 18, 2026.