Marvel Studios is set to bring back the Mad Titan Thanos in a highly anticipated MCU crossover project. Thanos served as the Infinity Saga's ultimate big bad, showcasing his journey as he retrieved the six Infinity Stones and successfully eliminated half of life in Avengers: Infinity War. The Avengers eventually defeated Thanos and his allies in Avengers: Endgame, but it came at a cost due to the deaths of two major pillars of the MCU, Tony Stark and Natasha Romanoff.
Endgame confirmed that Thanos is truly dead, but the Multiverse Saga managed to bring him back several times in Marvel's What If...? animated series and even made a quick cameo in Doctor Strange in the Multiverse of Madness. According to a report from insider Daniel Richtman, Thanos is set to return in Avengers: Secret Wars.
Thanos' major comeback in Secret Wars in 2027 would make it the Mad Titan's 7th movie appearance after The Avengers, Guardians of the Galaxy, Avengers: Age of Ultron, Avengers: Infinity War, Avengers: Endgame, and his corpse cameo in Doctor Strange in the Multiverse of Madness.
Thanos' return in Avengers: Secret Wars is exciting because it sets the stage for a potential matchup with Robert Downey Jr.'s Doctor Doom and interactions with the Fantastic Four and the X-Men.
Thanos also joins the long list of 17 characters confirmed or reported to appear in Secret Wars, such as Doctor Doom, Sadie Sink's mystery character, Tom Holland's Spider-Man, and Chris Evans' Steve Rogers.
Avengers: Secret Wars is set to premiere in theaters on December 17, 2027.
Every Villain & Reformed Villain Character Expected to Appear In Avengers: Secret Wars
Doctor Doom
As the replacement for Jonathan Majors' Kang the Conqueror, Doctor Doom is already confirmed as the main big bad of the Multiverse Saga, meaning that his return in Avengers: Secret Wars is inevitable. The announcement came during Marvel Studios' official Hall H panel at San Diego Comic-Con 2024 in July.
Doctor Doom's return in Secret Wars is terrifying because it strongly hints that he will win and fulfill his evil plans for the Multiverse, leading to the rumored Battleworld setting, where he is positioned as the ruler of his own planet. If so, it will take a lot to finally defeat Doom in Secret Wars.
Every surviving Avenger, New Avenger, Fantastic Four member, and X-Men will need to fully set aside their differences and execute a coordinated plan to shatter his dominance and reset the fractured Multiverse.
Winter Soldier
Bucky Barnes made his debut in Captain America: The First Avenger, but it wasn't until Captain America: The Winter Soldier that he returned as the villainous Winter Soldier, going up against his best friend, Steve Rogers.
After Steve did everything he could to help his closest friend, Bucky was fully redeemed just in time for the battle against Thanos.
Ahead of Avengers: Doomsday, Bucky became the founding member of the New Avengers in Thunderbolts*, meaning that he will serve as one of the leaders of the team in the fight against Doctor Doom.
Feige revealed in the same Marvel Studios Hall H panel at SDCC 2024 that the cast of Fantastic Four: First Steps and Thunderbolts* will return in both Doomsday and Secret Wars.
John Walker/U.S. Agent
Wyatt Russell's John Walker was initially introduced as Captain America's replacement in The Falcon and the Winter Soldier before turning into a full-blown villain at the end of the series.
Thunderbolts* fully redeemed Walker, making him a hero and a founding member of the New Avengers. Walker is already set to appear in both Avengers: Doomsday and Avengers: Secret Wars, meaning that he will play a crucial part in the heroes' clash against Robert Downey Jr.'s Doctor Doom.
Ava Starr/Ghost
2018's Ant-Man and the Wasp introduced Ava Starr as the main villain, a stealth assassin codenamed Ghost who clashed with Paul Rudd's Scott Lang and Evangeline Lilly's Hope van Dyne.
While she was redeemed in the end, Thunderbolts* revealed that she continued to work for Valentia Allegra de Fontaine, but eventually became a hero as a founding member of the New Avengers.
Ghost joins fellow reformed villains, Bucky and John Walker, in her upcoming return in both Doomsday and Secret Wars.
Sadie Sink's Character
Sadie Sink's mystery MCU villain character from Spider-Man: Brand New Day will reportedly appear in Avengers: Secret Wars after Deadline reported in November 2025 that the actress is part of the production of the Multiverse Saga's final movie.
Sink's inclusion in Avengers: Secret Wars led some fans to believe she is actually portraying the MCU's Jean Grey, since the character's significance in the grand scheme of things would require her to be part of such an event.
If true, then Sink's character in Spider-Man: Brand New Day is expected to survive and live to fight another day, setting the stage for her possible team-up with Tom Holland's Spider-Man.
