There's no denying it: Avengers: Infinity War will feature the largest cast for a Marvel movie yet. Building off everything that's happened in the Marvel Cinematic Universe since it launched in 2008, the movie will see the Avengers, Guardians of the Galaxy and more to fight the threat this franchise has been teasing for half a decade: Thanos. He's one of the greatest villains in the Marvel comics, and he'll finally prove why he's so formidable on the silver screen.
There's still a lot that hasn't been revealed yet about Avengers: Infinity War, including how it connects to 2019's Avengers 4. Fortunately, one area where there's plenty of information is castings. While Marvel is remaining tight-lipped on the new characters who will appear (including who Peter Dinklage and Terry Notary are playing), there have been numerous confirmations about characters who will be returning. Let's take a look at all the MCU heroes and villains who will definitely be back for Avengers: Infinity War.
Thanos
Thanos stayed on the sidelines for five years now, but in 2018, he'll finally prove why he's the overarching antagonist of the MCU. After several of his minions failed to retrieve the Infinity Stones on his behalf, the Mad Titan decided at the end of Avengers: Age of Ultron to take his Infinity Gauntlet out of the vault and secure them himself. If he succeeds, Thanos will be able rewrite all of reality, and like his comic book counterpart, he may be doing this to court Death.
Iron Man
Iron Man has been part of the MCU since the beginning, so it would be weird if he didn't participate in Avengers: Infinity War. Tony Stark has been through a lot over nearly a decade, from becoming a superhero and walking away from war profiteering to working with the government on registering enhanced individuals. Tony is still continuing his Iron Man duties and trying to keep the world safe, so bet on him being at the front lines and breaking out his best tech yet to fight Thanos.
Captain America
Captain America has been one of the MCU's most cherished heroes for decades, but as of Captain America: Civil War, Steve Rogers has abandoned his patriotic mantle and is on the run due to his anti-registration activities. Despite his current predicament, Steve is still someone who will do the right thing no matter what. So when Thanos comes to Earth, he'll jump back into action to keep the innocent safe, which hopefully means picking up his vibranium shield again.
Thor
Even though he hasn't been involved with the Avengers for a while, Thor's been keeping himself busy. Along with departing Earth at the end of Avengers: Age of Ultron to learn about the Infinity Stones, he also has to deal with what's coming up in Thor: Ragnarok, which includes finding Odin, surviving Sakaar and preventing Hela from destroying all of Asgardian civilization. The God of Thunder will be put through the ringer this fall, but rest assured, he'll be ready for battle during Avengers: Infinity War.
Hulk
Like Thor, Hulk's been out of the game for a little bit, but moviegoers will reunite with him in Thor: Ragnarok, where he'll battle Thor on Sakaar and then team up with the God of Thunder. Then he'll take part in both Avengers: Infinity War and Avengers 4, which, according to Mark Ruffalo, form with Ragnarok to make a standalone Hulk story. That's fine and dandy, but no doubt what many Marvel fans want most from the Green Goliath in this tale is for him to go mano a mano with Thanos.
Spider-Man
Spider-Man is a still new to the MCU, but his decades-long popularity has ensured that he's already a major player in the MCU. After being recruited by Tony Stark in Captain America: Civil War, Peter Parker is returning in Spider-Man: Homecoming to put his technologically-enhanced Spider-suit to good use and a gang of thieves with their own special tech, led by The Vulture. We don't know yet how that story will play out, but it certainly looks like it will strengthen Peter's character, making him a more effective superhero for when Avengers: Infinity War rolls around.
Star-Lord
Peter Quill was taken from Earth almost 30 years ago, and although he's led a life of excitement since then, he still hasn't returned to home. With two adventures under his belt with the other Guardians of the Galaxy, the self-named Star-Lord will finally have to head back to Earth in Avengers: Infinity War when Thanos starts wreaking havoc. Since he's been gone for so long, it will be interesting to see how Peter reacts to modern day pop culture, like learning how the Zune isn't the most popular music player like he was led to believe.
Gamora
Gamora was the first of Thanos' "children" to leave his side, and it's a good thing she did, because now she's putting her skills to good use as a Guardian of the Galaxy. Because of her time with the Mad Titan, Gamora will prove invaluable in fighting him and his forces during Avengers: Infinity War. Of course, since she was also Thanos' favorite daughter, that makes her betrayal sting even more for him, so if they cross paths, you can bet that "daddy" is going to have some words for Gamora, to put it as lightly as possible.
Drax
Drax the Destroyer helped with destroying Ronan, the Kree fanatic who killed his wife and daughter. However, Drax told Gamora at the end of Guardians of the Galaxy that Ronan was just a pawn, and for his vengeance to truly be carried out, he would need to kill Thanos. Drax's desire for revenge wasn't mentioned in Guardians of the Galaxy Vol. 2, but you can bet that if sees Thanos in Avengers: Infinity War, he'll try his hardest to eliminate the intergalactic warlord.
Nebula
It took Nebula a little longer to leave Thanos' side, and even longer for her to work out her issues with Gamora. Fortunately the sisters were on good terms by the time Guardians of the Galaxy Vol. 2 concluded, but rather than stick with the Guardians, Nebula departed to begin her quest to kill Thanos. She'll have to contend with Drax trying to fulfill that same objective, but at least we can count on Nebula being an ally during Avengers: Infinity War rather than trying to hurt the other Guardians.
Rocket
Rocket is arguably the biggest smart-ass in the MCU. Yes, dare I say it, even more so than Tony Stark. But after two Guardians of the Galaxy movies, he finally seems to realize that his connections to his fellow Guardians aren't easily broken. Now that his relationship fears have been dealt with, we can count on him providing his weaponry expertise in the showdown against Thanos. There's also concept art of Rocket fighting alongside Thor, so expect him to insult the God of Thunder's hair, or something along those lines.
Groot
It was fun seeing Baby Groot in action during Guardians of the Galaxy Vol. 2, but one of the sequel's mid-credits scenes showed that the walking and talking tree is still growing and currently in his teenage phase. Groot will still be in his adolescent phase during Avengers: Infinity War, though perhaps something in either this movie or Avengers 4 will trigger a growth spurt. In any case, if we're lucky, maybe we can see him and Hulk battling some of Thanos' goons side by side, though so far the only other Marvel hero seen alongside the Guardians of the Galaxy in this movie is Thor.
Mantis
Mantis spent most of her life being forced to serve Ego, but now that Peter Quill's father is no more, she has joined the Guardians of the Galaxy. It's unclear if her empathic abilities will come in handy during Avengers: Infinity War, but at least she can now help other with her power rather than serve a sinister Celestial. We also don't have to worry about her being killed off, as she'll be back with the other Guardians in Guardians of the Galaxy 3.
The Collector
Thanos isn't the only one who wants to gather the six Infinity Stones together. Taneleer Tivan, a.k.a. The Collector, has also been eagerly seeking those powerful artifacts, and even though he lost the Orb, a.k.a. Power Stone, when his collection was destroyed, he presumably still has the Aether, a.k.a. the Reality Stone, which he received in Thor: The Dark World. So far, we've only seen The Collector as an eccentric alien who enjoys gathering things for his museum, but maybe we'll see him show off some of his incredible powers in Avengers: Infinity War.
Vision
Vision is one of the newer superheroes in the MCU, but as far as Thanos is concerned, he's arguably the most important Avenger. Vision was born in Avengers: Age of Ultron when the Mind Stone was implanted in the synthetic body that contained J.A.R.V.I.S.'s programming. It's thanks to the Mind Stone that he's so powerful, but it also means that Thanos will immediately seek Vision out to rip the Stone from his forehead. One would assume this would kill Vision, but we won't know for sure until next year.
Loki
Loki struck an alliance with Thanos in The Avengers to secure the Tesseract, a.k.a. the Space Stone, in exchange for the Chitauri army conquering Earth for him. Not only did the Asgardian God of Mischief fail to deliver the Tesseract to the Mad Titan, his invasion was vanquished and he lost the Mind Stone in the process. Since then, Loki has taken over the Asgardian throne in Thor: The Dark World and will play an integral role in Thor: Ragnarok, but we don't know yet how he'll fit into Avengers: Infinity War.
Doctor Strange
Most of the special abilities in the Marvel Cinematic Universe have stemmed from science or cosmic forces, but Doctor Strange fully pulled back the curtain on magic and mysticism. Now that he's the master of New York's Sanctum Sanctorum, Stephen Strange has been keeping track of individuals who could threaten Earth, and Thanos is likely at the top of the list. The Avengers and Guardians of the Galaxy certainly aren't lacking for brute force, but maybe Doctor Strange's magic could be integral to defeating the Mad Titan.
Black Panther
T'Challa inherited the Black Panther mantle after his father was killed in Captain America: Civil War, and now that T'Chaka's murderer (Helmut Zemo) is in prison, the prince has gone back to his homeland, Wakanda. The Black Panther movie will follow T'Challa as he battles sinister forces aiming to bring down the Wakandan kingdom, but he won't have long to rest after afterwards, because he'll be participating in Avengers: Infinity War only a few months later.
Black Widow
Black Widow has been one of the MCU's most popular superheroes since being introduced in Iron Man 2, and while she still hasn't been given her own solo movie yet, she remains an important character in these ensemble pieces. When we last saw Natasha Romanoff, she'd gone on the run after helping Steve Rogers and Bucky Barnes escape. Black Widow is skilled at staying hidden, but we suspect that when Thanos arrives on Earth, she'll return to help her comrades.
Scarlet Witch
Scarlet Witch is one of the most powerful humans on Earth, but she was still captured during Captain America: Civil War's airport battle. Thankfully, Steve Rogers freed her and the other anti-registration supporters from The Raft. It's unclear whether Wanda Maximoff accompanied Steve and Bucky Barnes to Wakanda, or decided to avoid the authorities solo, but when Avengers: Infinity War unfolds, hopefully her psionic abilities will help even the playing field in this epic battle.
Falcon
Falcon has been loyal to Steve Rogers ever since they met in Captain America: The Winter Soldier, so it was no surprise to see the winged hero fight by the Star Spangled Avenger's side in Captain America: Civil War. Now that Sam Wilson is no longer imprisoned on The Raft, it's likely he's continuing to fight the good fight with Captain America in secret, but you can count on Sam busting out his wings and Redwing drone to battle Thanos' minions.
Winter Soldier
At the end of Captain America: Civil War, Bucky Barnes was still on the run from the world's governments for his past crimes as the brainwashed Winter Soldier. Seeking refuge in Wakanda with Steve Rogers, Bucky decided to go back into cold storage until the Wakandan scientists could figure out how to overwrite HYDRA's lingering programming. While there's been some fan speculation that Bucky could reawaken during the Black Panther movie, it's more likely he'll be thawed sometime during Avengers: Infinity War.
Nick Fury
Even though he's no longer S.H.I.E.L.D.'s director, Nick Fury has been continuing his spy activities following Captain America: The Winter Soldier. He reemerged in Avengers: Age of Ultron to help evacuate Sokovia, but his whereabout since then haven't been revealed. Hopefully Avengers: Infinity War will shed light on what he's been up to, but at the very least, it will be good to see him reunited with the superhero group he recruited years ago.
Maria Hill
After S.H.I.E.L.D. fell apart (well, on the big screen, at least), Maria Hill went to work for Tony Stark, and she was seen aiding Earth's Mightiest Heroes in Avengers: Age of Ultron. Despite helping set up the team's new base in New York, Maria was nowhere to be see in Captain America: Civil War, so it's unclear if she's still working with them, focusing solely on Stark Industries business or is operating elsewhere. In any case, her secret agent skills may prove valuable during the big event.
Wong
Wong was one of Stephen Strange's three mentors in Doctor Strange, and with The Ancient One dead and Karl Mordo taking power away from sorcerers, Kamar-Taj's librarian is now the former surgeon's closest magical ally. Wong is also familiar with the Infinity Stones, as he identified the Eye of Agamotto as being one of them (the Time Stone) to Stephen. With the Eye back in its resting place, perhaps Wong will be the one defending it when Thanos tries to steal it.
M'Baku
In the comics, M'Baku, better known as Man-Ape, is one of Black Panther's chief villains. All that's been revealed about the MCU's M'Baku is that he's the leader of a rival Wakandan tribe, so it remains to be seen if he'll be an antagonist in the Black Panther movie (like Erik Killmonger and Ulysses Klaue) or merely have differing views from the hero. In any case, we can expect him back for Avengers: Infinity War, and if we're lucky, he'll put aside his differences with T'Challa and defend Wakanda from Thanos' army.
Okoye
We learned a little bit about the Dora Milaje in Captain America: Civil War, and all indications are that we'll learn even more about them when Ryan Coogler opens the doors to Wakanda in his Black Panther movie. As that happens, we'll get closer to Okoye, the leader of this military group and a fiercely loyal supporter of King T'Challa. If the battle against Thanos works its way to Wakanda (as is expected), then Okoye will fight alongside Black Panther and the rest of the Avengers -- as it has recently been confirmed that actress Danai Gurira will, in fact, be part of the Avengers: Infinity War cast.
Proxima Midnight
Thanos is the ultimate big bad that the Avengers and Guardians of the Galaxy will have to face-off against in The Avengers: Infinity War - but the Mad Titan isn't totally alone in his quest to assemble the Infinity Gauntlet. Rather, he actually has a group known as the Black Order that is dedicated to helping him take over the universe. Proxima Midnight is one member of this four-person team and is not only an immensely skilled warrior, but can do some serious damage with the powerful spear that she likes to chuck around.
Corvus Glaive
Corvus Glaive is the second member of Thanos' Black Order, and is actually the husband of Proxima Midnight. He is considered the leader of the Mad Titan's subordinates, and serves as the purple alien's right-hand man. His name actually comes from the weapon he wields - a glaive - and just by itself it makes him a seriously scary threat. As you can see in the image above, it has the power to cut through anything, including Vision's head, presumably allowing him access to the precious Mind Stone.
Ebony Maw
Another member of the Black Order, Ebony Maw is admittedly not much of a physical threat, As you can see, he's not exactly super ripped. That, however, should not make you underestimate just how powerful he is. He may not have giant muscles, but what he does possess is a special power of persuasion - able to whisper in ears and get things done. So while Iron Man or Captain America could just punch him in the face to knock him out, they are in serious trouble if he successfully sneaks up on them and starts telling them what to do.
Black Dwarf
Also known as Cull Obsidian, Black Dwarf is the fourth and final member of the Black Order - and kind of the opposite of Ebony Maw. He is by far the biggest of Thanos' minions, and able to throw a seriously hefty punch that even Hulk would be affected by. With his might combined with his teammates' combined strength, the Avengers and Guardians of the Galaxy are definitely in trouble.
