Out of all the Marvel Studios news at the recent D23 Expo, the biggest reveal by far was the announcement of the team lineup for the upcoming 2024 Thunderbolts movie, featuring the return of Bucky Barnes, Yelena Belova, US Agent, Taskmaster, and more. However, one major question is still up in the air: who exactly will this new team be fighting?

The Marvel Studios panel at D23 confirmed that the Thunderbolts, the Marvel Cinematic Universe’s latest superhero team, will make their debut in Captain America: New World Order, in which they’ll presumably be teaming up with Sam Wilson against the Leader. But currently, it’s still a complete mystery who the main antagonist of the Thunderbolts movie will be. Here are a few candidates for the film’s big bad, some of whom are more likely than others.

RELATED: Marvel Unveils Its Thunderbolts Lineup at D23

Baron Zemo

Dancing Zemo

One of the biggest surprises of the Thunderbolts cast announcement was the complete lack of fan favorite villain Baron Zemo, previously featured in Captain America: Civil War and The Falcon and the Winter Soldier. As soon as the Thunderbolts movie was announced, many fans considered Zemo to be a shoo-in for the team lineup. After all, he was the team’s original leader in the comics, and remains widely associated with the group to this day. However, it’s possible that Zemo will still be in the film — just as its antagonist rather than its protagonist.

Looking at the Thunderbolts’ recently announced roster, every single member of the team is some form of Super-Soldier. There’s the former Winter Soldier, an ex-Captain America, three Red Room operatives, and a superpowered SHIELD assassin. So considering Zemo’s dogmatic hatred for Super-Soldiers, it’s only natural that he’d be the Thunderbolts’ nemesis rather than their leader. Plus, with both Bucky and US Agent now confirmed, Zemo already has a personal connection to two of the team’s members. Out of all the villains on this list, Baron Zemo is arguably the most likely candidate — some might even say it’s not really a Thunderbolts movie without Zemo.

Count Nefaria

Count-Nefaria-Marvel

Alternatively, with a protagonist cast consisting entirely of previously established characters, it’s possible that an all-new villain could be introduced as the Thunderbolts’ nemesis. One possible candidate is Count Nefaria, a superpowered crime lord who was first created as an Avengers villain by Stan Lee and Don Heck all the way back in 1965. Since then, however, Nefaria has crossed paths with several other heroes, including the Thunderbolts. He’s a relatively prominent villain who has yet to appear in the MCU, so he’d be an effective pick for the main villain of Thunderbolts.

Red Hulk

red hulk marvel comics

It was theorized for years among MCU fans that Thaddeus “Thunderbolt” Ross, played by William Hurt, would eventually gain his own Gamma powers and become the Red Hulk, just like his comic book counterpart. Some fans even predicted that he’d found his own Thunderbolts squad, just as he did in the team’s 2012-2014 comic run. Granted, those theories largely went when Hurt passed away earlier this year, but the possibility of Ross being recast isn’t out of the question.

Under most circumstances, this possibility wouldn’t be worth mentioning. But as previously stated, the Thunderbolts will make their MCU debut in Captain America: New World Order, which will also see the return of Tim Blake Nelson as Samuel Sterns, aka the Leader. Traditionally portrayed as the Hulk’s archnemesis, the Leader’s appearance in the Thunderbolts’ debut film could mean a potential connection between the team and another Hulk antagonist, who has a much closer history with the group in the comics. But once again, none of that means much unless the late William Hurt is recast as Ross.

Doctor Doom

Doctor-Doom-Comic-Cover-Lightning-Bolt

The name of Victor Von Doom has been on every MCU fan’s lips ever since an adaptation of Secret Wars — one of Doom’s biggest comic storylines — was confirmed to be the grand finale of Phase Six. But if Doctor Doom is indeed the true villain of the Multiverse Saga, then like Thanos before him, it’s likely that he’ll make a few scattered appearances before he takes center stage at the Saga’s end. And what better way to establish him as the MCU’s biggest new villain than by centering the final film of Phase Five around him? Of course, Doctor Doom is far too powerful for any of the Thunderbolts to fight directly, but considering the team’s shared espionage background, a spy mission to Doom’s kingdom of Latveria would make perfect sense as the film’s premise.

In fact, if another prominent fan theory is to be believed, then Bucky’s previous adventures have already planted the seeds for an encounter with Doom. It’s briefly mentioned in The Falcon and the Winter Soldier that after Sokovia was devastated by Ultron, the country was divided into pieces and annexed by neighboring countries. Many fans believe that one of these countries could be Latveria, another fictional Eastern European country in the Marvel Universe. But even if this theory ends up being false, it’d still be a treat to see the Thunderbolts take on a mission to Latveria.

Contessa Valentina Allegra de Fontaine

contessa valentina allegra de fontaine in falcon and winter soldier episode 5

Finally, it’s entirely possible that the film’s main antagonist could be hiding in plain sight. The enigmatic Val, played by Julia Louis-Dreyfus, is a representative of an unknown organization that seems to be assembling its own super-team — that team being, of course, the Thunderbolts. She’s already established ties with both Yelena Belova and US Agent, and it seems that more recruits won’t be far behind. However, Val’s true reason for assembling the Thunderbolts is still a mystery, and it likely isn’t anything altruistic. In the comics, Valentina started out as Nick Fury’s love interest and an ally of SHIELD, only to be revealed as a mole for Hydra in the 2011 Secret Warriors series written by Jonathan Hickman. If the MCU’s Val truly is an agent of Hydra, then none of the Thunderbolts will take it well if they find out — especially Bucky.

MORE: Will Doctor Doom Be The True Villain Of The Multiverse Saga?