The original six Avengers team were at the center of almost every major event that followed. Other superteams popped up throughout the first three Phases, such as the Guardians of the Galaxy, but the MCU could have an abundance of superhero teams in the near future.
Marvel Studios has announced a full slate of movies and Disney+ shows that will make up Phase 4, with some properties potentially being Phase 5 titles too. This will see characters like Doctor Strange (Benedict Cumberbatch), Captain Marvel (Brie Larson), and Spider-Man (Tom Holland) take on more prominent roles in the MCU with new solo films. But, Marvel is also going to introduce a lot of new heroes, like Yelena Belova (Florence Pugh), Shang-Chi (Simu Liu), Blade (Mahershala Ali), and the Eternals. In almost every instance, these characters should go on to have major roles in the MCU and will likely team up with other heroes in a variety of ways.
With so many new characters ing the MCU in Phase 4, the lack of an official team-up movie on the slate is all the more surprising. However, just because Avengers 5 isn't officially announced doesn't mean that Marvel hasn't already been busy building rosters for their next wave of superteams. Some might not realize it yet, but the MCU is already in the process of rounding out the rosters for quite a few superhero teams.
New Avengers
Marvel Studios might not have Sam Wilson aka Captain America (Anthony Mackie) can lead the team after previously spending time with the team as Falcon, and Scarlet Witch (Elizabeth Olsen) could also return to the team potentially. Doctor Strange and Captain Marvel are also likely to land on the next Avengers roster. But, this should also be a place for other characters to become official, main of the squad. New Phase 4 characters like Shang-Chi, Mighty Thor (Natalie Portman), Black Knight (Kit Harington), Sersi (Gemma Chan), and others are strong options to be included.
Young Avengers
The The Falcon and The Winter Soldier to possibly set him up as well.
Female Avengers
There has been a lot of talk about an all-female Avengers team-up in the MCU's future, and Marvel Studios already has a stacked cast waiting to come together. Captain Marvel, Scarlet Witch, Wasp (Evangeline Lilly), Shuri (Letitia Wright), Okoye (Danai Gurira), Valkyrie (Tessa Thompson), Gamora (Zoe Saldana), Nebula (Karen Gillan), Mantis (Pom Klementieff), and Pepper Potts (Gwenyth Paltrow) already worked together briefly in Avengers: Endgame. They are all expected to be in consideration for an all-female Avengers film. The roster could also be expanded to include Phase 4 heroines like She-Hulk (Tatiana Maslany), Mighty Thor, Yelena Belova, Sersi, Thena (Angelina Jolie), Makkari (Lauren Ridloff), and Ajak (Salma Hayek).
Thunderbolts
One superhero team the MCU is subtly assembling throughout Phase 4 is the Thunderbolts. The return of Baron Zemo (Daniel Brühl) for The Falcon and The Winter Soldier could kick off the entire charade behind the team's formation. Since the villain team has had many iterations in the comics, Marvel could mix and match established characters for the MCU's Thunderbolts team. Some characters who could be in consideration to Zemo include Yelena Belova, Thunderbolt Ross (William Hurt), Ghost (Hannah John-Kamen), Taskmaster, The Abomination (Tim Roth), and Bucky Barnes (Sebastian Stan).
Midnight Sons
The MCU also has the building blocks for the Midnight Sons to form at some point in the near future. Marvel's supernatural-focused team will surely include Doctor Strange should they be introduced in the MCU. This would also be a place for Blade to be included in a big crossover, as well as Moon Knight (Oscar Isaac) after his Disney+ series. Wong (Benedict Wong) has also been part of the team in the comics. There are currently rumors that fellow like Brother Voodoo, Werewolf by Night, and Ghost Rider are in consideration to the MCU before too long. Perhaps the Midnight Sons could even be a way for Jon Bernthal's Punisher to the MCU.
Illuminati
Black Panther 2. But, it also might not be long before Reed Richards or Professor X are part of the MCU and find themselves tied to the Illuminati either.
Champions
One superhero team slowly making its way to the MCU at the moment is Champions. The young hero team was formed by Kamala Khan, Miles Morales, and Sam Alexander after their stints with the actual Avengers. So far, only Ms. Marvel is cast in the MCU, with Iman Vellani cast as Kamala for the Disney+ show. There have been rumors, though, that Miles could the MCU before too long, with WandaVision also presenting Marvel with the chance to introduce Vision's AI daughter Viv. This is also a team that Riri Williams aka Ironheart has been part of, and she's also been rumored to be coming to the MCU.
Ultimates
After the events of Avengers: Endgame, the MCU might not be too far away from founding a superteam with a cosmic focus. Captain Marvel founds the team in the comics and the Ultimates could go hand-in-hand with her longtime friend Nick Fury (Samuel L. Jackson) starting SWORD. The MCU will put Monica Rambeau (Teyonah Parris) in a position to the team through WandaVision and we could see Shuri take T'Challa's place on the roster. America Chavez will also be around by the time Phase 4 concludes, leaving just Blue Marvel and possibly Galactus to be introduced to get the Ultimates ready for a place in the MCU's future.
