The Marvel Cinematic Universe continues to expand. Even though the historic franchise skipped out on Hall H at this year's SDCC, there are nevertheless big plans underway for Phase Five. There have been a long list of characters that joined the Avengers since Iron Man (2008) premiered.
There are more than a few characters on this list that have easily earned the title of "Avenger," like Wong (Benedict Wong), but whether it is due to circumstances or of their own choice, they haven't officially joined the team. However, they may have joined up with Earth's Mightiest Heroes once or twice.
Valkyrie becomes a king and strong ally to Thor
Found as a Scrapper on the planet of Sakaar by Thor (Chris Hemsworth), Valkyrie was a part of The Valkyries, before they were defeated by Hela (Cate Blanchett). She is now the King of New Asgard and Thor's right-hand partner, assisting him in taking down Hela in Ragnarok and Gorr (Christian Bale) in Love and Thunder.
She has undergone quite the transformation from the selfish alcoholic on Sakaar to a benevolent leader of New Asgard, a role that Thor could not do himself post-snap. After the events of Love and Thunder, she is seen training the children of New Asgard to be warriors and defend themselves.
Moon Knight's uneasy relationships make him a big question mark
Hard to say where Marc Spector/Steven Grant (Oscar Isaac) will align with the rest of Marvel's roster. Although Marc was released by Khonshu (F. Murray Abraham) at the end of the Moon Knight series on Disney+, a third identity (Jake Lockely) appeared to still be aligned with the Moon God.
Oscar Isaac gave a great performance and brought life to two very different characters. He'll team up with the Avengers at some point, but given his violent tendencies and split personalities, it seems more likely he is a guy who comes in off the bench, more than be in the starting lineup.
Happy Hogan was a rock for both Iron Man and Spider-Man
Tony Stark's (Robert Downey Jr.) bodyguard and best friend, Happy (Jon Favreau) became Peter Parker's (Tom Holland) go-to for anything superhero related after Tony's death in Avengers: Endgame (2019). He also sparked up a brief romance with Aunt May (Marisa Tomei).
Happy is loyal and, although he provides comic relief, he has shown to be reliable in a jam and is very competent when it comes to aiding superheroes, whether it is Iron Man or Spider-Man. Happy is also a very sympathetic character, the three people he was closest to: Tony, May and Peter, are all gone (his memory of Peter was erased). That cheeseburger line still hits home.
The Man Without Fear is getting the MCU treatment
Daredevil's (Charlie Cox) revival in the MCU was recently announced at San Diego Comic Con as Daredevil: Born Again. The first three season that were on Netflix are canon, and the subtitle 'Born Again' will serve as the first season under Disney. Matt Murdock may have some experience teaming up with The Defenders, but it's unsure how big of a role he'll have with the Avengers.
He made his first appearance as Peter's lawyer in No Way Home (2021), which definitely teased a possible future team up between the Man Without Fear and the Friendly Neighborhood Spider-Man, who patrol Hell's Kitchen and Queens.
Bucky Barnes was always on the run
Not until Infinity War was Bucky (Sebastian Stan) considered an ally to The Avengers. He was the primary antagonist in Captain America: Winter Soldier (2014) and was framed for a bombing by Zemo (Daniel Brühl) in Civil War (2016) After those events, Captain America (Chris Evans) took his friend to Wakanda to undo the decades of brainwashing the Russians did on him.
Bucky made his return to action to help T'Challa (Chadwick Boseman) and the rest of the Avengers fight off Thanos (Josh Brolin) in Wakanda to stop him from taking the Mind Stone from Vision (Paul Bettany). Post Endgame, Bucky was attempting to atone for his mistakes as the Winter Soldier, he also finally found a friend in Sam Wilson (Anthony Mackie).
Wong is the Sorcerer Supreme, and leader of Kamer-Taj
With Doctor Strange (Benedict Cumberbatch) being dusted from The Snap, Wong became the Sorcerer Supreme, and is the leader of Kamer-Taj. Although Strange could be considered the stronger sorcerer, with Wong assuming duties as Sorcerer Supreme, that leaves Strange to be more involved with The Avengers.
Of course, Wong will always be there to assist Strange whenever he needs, but it seems like he has had something brewing on his own, as he has been shown to be with Abomination (Tim Roth), and recruiting Shang-Chi (Simu Liu) in Shang-Chi and the Legend of the Ten Rings (2021).
Loki has one of the best character arcs in the MCU
Loki (Tom Hiddleston) is definitely considered a villain of The Avengers in the early part of the MCU. But he slowly turned into an ally during the events of Thor: Ragnarok. Even after he died at the hands of Thanos, his variant 2012 version in the self-titled Disney+ show underwent the same development.
Loki is still very much a trickster and has a general love of chaos, but he isn't the "take over the world and enslave humanity" villain he once was. He became quite the hero alongside his variant counterpart, Sylvie. Although, he was unable to stop her from killing He Who Remains, a variant of Kang the Conqueror (Jonathan Majors).
Shang-Chi can be a big player in the MCU
Shang-Chi is the son of Xu Wenwu (Tony Leung) aka The Mandarin, the real one, not the fake one that was used in Iron Man 3. Wenwu was granted immortality by the Ten Rings, the item he named his army after. When his wife was murdered, he trained his children to be assassins to seek revenge. They both ended up turning on him as he lost his mind.
After the events of Legend of the Ten Rings, Shang-Chi is now in possession of the mystical item. During the post-credit scene, he is taken to Kamer-Taj by Wong, where it is discovered the Ten Rings are emitting a signal to something unknown. Banner (Mark Ruffalo) welcomes Shang-Chi "to the circus," but it will be interesting to see how involved with The Avengers he is, or if he'll be a part-timer like Doctor Strange was.
The Black Panther is forever a king
T'Challa was already The Black Panther during the events of Civil War, and became the King of Wakanda after the death of his father during a bombing orchestrated by Zemo. Wakanda's history had been solely aligned with their people, and keeping their advanced society a secret.
However, after the death of Erik Killmonger (Michael B. Jordan), who sought to use Wakanda's power to liberate oppressed people around the world and wage a war against the oppressors, T'Challa realized he had to open Wakanda's borders in order to benefit the world. He also assisted The Avengers during Thanos's hunt for the Mind Stone. The devastating death of Chadwick Boseman was addressed in the emotional 2022 film Wakanda Forever.
The Guardians of the Galaxy are space-bound, not Earth-bound
The Guardians are their own squad that work on their own vibe. The Avengers are an Earth based group, hence the "Earth's Mightiest Heroes" tagline. Except Rocket Raccoon and Nebula during the five-year blip period, who joined what was left of The Avengers.
After teaming up during Infinity War and Endgame, The Guardians left with Thor to search for the alternate Gamora, who came through the Quantum Realm with Thanos from 2014. All things considered, they've only had a very brief meeting with The Avengers, including Tony Starks funeral.