There are more super hero movies coming out in the next 5 years than almost anyone ever thought possible just a decade or two ago. The famed DC comics properties are now rallying for a barrage of movies aimed at building their characters up to a Justice League movie. Even Fox’s use of the X-Men section of the Marvel universe is spinning up to several distinct branches and interwoven stories – including possibly two distinct timelines. But, with all the costumes, explosions, and special powers, there is only one movie that really has the public’s attention this summer: the sequel to the blockbuster Avengers, entitled Avengers: Age of Ultron.

The main cast of the film has pretty well been set since Mark Ruffalo was cast as Bruce Banner/ The Incredible Hulk way back before the first Avengers. But even since series newbies James Spader, Elizabeth Olsen, and Aaron Taylor-Johnson were announced, Marvel has slowly been rolling out additional cast members in a variety of supporting roles. Each new addition has been a world-class actor or superstar in their own right. Avengers: Age of Ultron stands poised to become either the superhero movie equivalent of Pulp Fiction or a hard-to-follow mess with two many famous faces to follow. We’re hoping for the former. For those not following the epic geekery on a weekly basis, let’s dissect what we know and how it stands to impact the film (spoiler free of course).

The Main Cast

The actors we knew even before the first Avengers film was released would be returning. The main group’s original team is all intact for this film.

Robert Downey Jr. as Tony Stark/Iron Man
RDJ’s Tony Stark has become the team’s semi-unofficial benefactor this time around, co-leading the group with Captain America following the demise of S.H.I.E.L.D. in Captain America: The Winter Soldier. Stark continues to tinker with advanced technology to try to help in their efforts to keep the world safe.

Chris Evans as Steve Rogers/Captain America
Steve Rogers was the driving factor in the dissolution of S.H.I.E.L.D. following the reveal that HYDRA had been perverting it over several decades. He co-leads the Avengers with Tony Stark.

Chris Hemsworth as Thor Odinson
Hemworth returns as The Mighty Thor following the character’s refusal to become king at the conclusion of Thor: The Dark World. In that finale, Thor was apparently unaware that his step-brother Loki was, in fact, still alive and secretly pretending to be Thor’s father Odin. Thor has returned to Earth, apparently to protect it and be closer to his love, Jane Foster.

Mark Ruffalo as Bruce Banner/Hulk
Lou Ferrigno as the voice of the Hulk
Ruffalo’s wonderfuly understated performance of Bruce Banner set the stage for him to become an intellectual partner in crime with Tony Stark. Think of him as a less flashy, more thoughtful complement to Stark’s endless witticisms and snark. 80s TV fans can rejoice as Lou Ferrigno has returned to do the voice acting for when Banner’s rage becomes inconsolable and turns him into the Hulk.

Scarlett Johansson as Natasha Romanoff/Black Widow
Following the demise of S.H.I.E.L.D., Natasha Romanoff has fully departed agent work and is now a full-time part of the Avengers. Johansson will also reprise the role in Captain America: Civil War.

Jeremy Renner as Clint Barton/Hawkeye
First introduced in Thor, Jeremy Renner spent most of his screen time as Hawkeye in the first Avengers film in a hypnotized state (Loki used the Chitauri sceptor to brainwash him). This film, director Joss Whedon has promised a lot more of Hawkeye in the story, and a lot more to Hawkeye’s backstory.

Supporting Cast

A slew of top-tier actors make up the main supporting cast of the film. Many have been introduced in other Marvel Cinematic Universe films. Some are new to the universe introduced here in AAOU.

Aaron Taylor-Johnson as Pietro Maximoff/Quicksilver
Aaron Taylor-Johnson plays Pietro Maximoff (known to comic fans as Quicksilver) part of the brother-sister duo with the Scarlet Witch. Johnson plays Quicksilver alongside Elizabeth Olsen, with whom he also starred in Godzilla. The siblings role is nebulous as they may not be exactly on the side of the Avengers. In the post-credits scene at the end of Captain America: The Winter Soldier the two are shown on a ship run by Baron von Strucker, apparently being experimented on somehow in connection with the Chitauri scepter.

Elizabeth Olsen as Wanda Maximoff/Scarlet Witch
Quicksilver’s sister Wanda, played by Elizabeth Olsen, has a variety of psionic powers under the moniker the Scarlet Witch. While their part in the story is still mostly secret, apparently the Scarlet Witch is able to inject herself into people’s minds, stirring up their greatest fears. Don’t be surprised if this is how the Hulk and Iron Man end up fighting each other, as seen in the Ultron trailers.

Don Cheadle as James Rhodes/Iron Patriot
The character of James Rhodes, best friend to Tony Stark, here returns aligned with the Avengers. In the latter two Iron Man movies, Don Cheadle’s character took control of one of Stark’s Iron Man suits and re-labeled it the Iron Patriot (or War Machine, depending on what part of the movie you watch). It’s not known for sure if Iron Patriot will fully be a member of the Avengers, but in the first trailer released he was shown joking and laughing with them at a party at the Stark tower.

Paul Bettany as J.A.R.V.I.S. and The Vision
Paul Bettany, along with Robert Downey Jr., was one of the very first actors to take part in the proper Marvel Cinematic Universe. Bettany voiced Tony Stark’s snarky A.I. computer system J.A.R.V.I.S. (fans of the Agent Carter series will now be firmly aware of the genesis of that name). Bettany is now playing double duty, portraying a different kind of robotic character, the mysterious android known as The Vision. Marvel has kept this character’s part in the story under close wraps. Only two hard-to-see images of what the character will look like have surfaced. One of them is the close-up above.

Cobie Smulders as Maria Hill
Maria Hill (portrayed by How I Met Your Mother actress Cobie Smulders) was originally introduced in the first Avengers film. Since, she has become a supporting character in any Marvel story directly involving S.H.I.E.L.D. such as TV’s Agents of S.H.I.E.L.D. or Captain America: The Winter Soldier. The last we saw of her in the films, during the ending scene Winter Soldier, she was apparently interviewing for a position at Tony Stark’s Stark Industries. In the first trailer for Avengers: Age of Ultron she is seen sitting next to Hawkeye while they’re joking about trying to pick up Thor’s hammer.

Anthony Mackie as Sam Wilson/Falcon
It’s not known to what extent he’ll be an active participant, but Anthony Mackie’s Sam Wilson is also going to be a part of Avengers: Age of Ultron. Near the final act of Captain America: The Winter Soldier, Mackie revealed his identity as Falcon, making use of a military-grade piece of wing technology that literally allows him to fly. At the close of that movie, Falcon and Captain America are going to hunt for Steve Rogers’ horribly-experimented-on friend Bucky Barnes, on the lam as the titular Winter Soldier.

Stellan Skarsgård as Erik Selvig
Originally introduced in the first Thor movie as a close friend and mentor to Natalie Portman’s Jane Foster, Stellan Skarsgard’s Erik Selvig has always been a funny and grounded part of the story. In Avengers he was fully brainwashed by Loki, and it was his scientific genius that allowed Loki to use the Tesseract to open the portal that brought the Chitauri to Earth in the Battle of New York. (And if that wasn’t the single geekiest sentence ever written…I’m not sure I want to read what is.) Following that, Selvig struggled to regain his sanity in Thor: The Dark World. His role in this story is still a secret, though odds are he will be closely allied with Thor due to Thor’s love for Jane Foster.

James Spader as Ultron
Ultron is the primary villain in this new Avengers movie. A longtime villain in the comic books hell-bent on destroying the Avengers and humanity, Ultron is known to be able to completely rebuild himself, each time stronger and more invulnerable than the last. In the comics, Ultron was originally created by Hank Pym (Ant-Man). In this story, his origins are different, most likely created due to some flaw in Tony Stark’s robotic peacekeeper program. Ultron is voiced by the incomparable James Spader, known most recently for his hit role on The Black List.

Samuel L. Jackson as Nick Fury
Samuel L. Jackson holds the record as the actor in the most films of the Marvel Cinematic Universe. This will be his sixth. First introduced in the post-credits scene of Iron Man, his character Nick Fury was, for most of the story, the Director of S.H.I.E.L.D. At the close of Captain America: The Winter Solider, he helped Steve Rogers, Falcon and Black Widow dismantle the organization following the discovery of HYDRA’s role in it. It’s unclear how he will be involved in the story here, but likely it will be some type of philosophical guidance.

The Deep Cast

Things from here on out get really murky, as Marvel and Joss Whedon have a ton of tricks and surprises up their sleeves. We’ll do our best to recap, but there’s little confirmation here beyond that these actors are indeed in the movie.

Thomas Kretschmann as Baron Wolfgang von Strucker
Another mystery of Avengers: Age of Ultron is the appearance of Baron von Strucker, played by Thomas Kretschmann. Baron von Strucker first appeared in the aforementioned credits of Captain America: The Winter Soldier and hinting at a secret HYDRA program involving the Chitauri scepter that has already caused the deaths of many volunteers. Given the presence of Quicksilver and Scarlet Witch, it’s likely the twins’ superpowers are a result of those experiments.

Kim Soo Hyun (A.K.A. Claudia Kim) as Dr. Cho
Hardcore fans noticed someone standing with the Avengers at the party in the first trailer for the movie. Later, this character was reveled to be a Dr. Cho portrayed South Korean actress Claudia Kim. Nothing is known of her part in the story except that she is somehow involved in technology development with Tony Stark.

Hayley Atwell as Peggy Carter
Agent Carter fans are well familiar with Hayley Atwell’s Peggy Carter. First introduced in Captain America: The First Avenger, Carter and Steve Rogers fall in love, but are separated almost permanently following the Captain’s disappearance in the Arctic ice. They are reunited in Captain America: The Winter Soldier, but it is late in Carter’s life and she is apparently grappling with some form of memory loss or dementia. It’s unclear whether her part will be a flashback or another look at her in the winter of her years.

Tom Hiddleston as Loki Laufeyson
Arguably the best villain in the Marvel Cinematic Universe, Tom Hiddleston’s portrayal of Loki pretty much steals every scene he shows up in. After being defeated in the first Avengers film, he had a major part in Thor: The Dark World, ultimately faking his own death and somehow displacing Odin. The finale of the movie shows him using his tricks to pretend to be Odin. It’s not known what his part in this film will be, but his and Idris Elba’s appearance was outed by Elba in an interview late last year.

Idris Elba as Heimdall
As just mentioned, Idris Elba outed his own involvement in the movie, explaining he had a scene with Tom Hiddleston. Elba was apparently unhappy having to continue to play the admittedly marginal part of Heimdall after the serious subject matter he enjoyed playing Nelson Mandela in Mandela: Long Walk to Freedom. It’s not known whether this scene is part of a dream sequence, or whether it pertains to the unraveling of Loki’s deception in Asgard. We wouldn’t rule out this being the post-credits scene, either.

Andy Serkis as Ulysses Klaue
Smart fans noticed a small cameo in the first Avengers: Age of Ultron trailer, and even placed the character. Marvel has been cagey with the details until just this week, but the fans were right, this is Andy Serkis playing Ulysses Klaue (or Ulysses Klaw as he is known in the comics). His part in this story has been described as minimal, but apparently this is the setup for a larger role down the line, likely to be the main villain in the upcoming Black Panther movie starring Chadwick Boseman.

Julie Delpy as ???
The latest news as of this week is that not only Julie Delpy, but also Linda Cardellini apparently have parts in the upcoming film. The news was leaked through a red-carpet press premiere invite to media, stating that the two are appearing as cast members. Disney confirmed to Slashfilm the two being listed was not a misprint. It’s unknown what party Delpy will play, but fans will remember her from her part in the Before trilogy films with Ethan Hawke and An American Werewolf in Paris.

Linda Cardellini as ???
Like Delpy, it is unknown at this time what part Linda Cardellini will play in the film. Fans will remember her for excellent part in the short-lived Freaks and Geeks Judd Apatow TV series and more recently for playing Sylvia Rosen on Mad Men.

Rumors and Unconfirmed Information

Beyond this point, all is rumor and speculation. Director Joss Whedon has merely hinted lately that there will be a lot more surprise appearances in Avengers: Age of Ultron than anyone expects. Though, no details have come out about what that means. Naturally Internet speculation has run wild, guessing everyone from the new Carol Danvers Captain Marvel to Spider-Man will appear. Many have wondered if Natalie Portman or Gwyneth Paltrow will appear reprising their respective roles, and there are even wild unsubstantiated rumors about Mel Gibson and Jodie Foster. Believe nothing until the facts have been revealed, but know there will undoubtedly be surprises. Heck, even Seth Green had a tiny part in Guardians of the Galaxy, so anything is possible.

Josh Brolin as Thanos
One rumor that is likely is Josh Brolin reappearing as the mad titan Thanos. Thanos first appeared as a cameo in the mid-credits scene in the first Avengers film. The wink to fans that this was obviously the beginning of a massive story leading to the Infinity Gauntlet saga. This has been proven true by Marvel’s announcement that the end of phase three of the Marvel Cinematic Universe will be a two-part conclusion Avengers: Infinity War. Josh Brolin formally took the role on in a speaking capacity as a sub-thread in Guardians of the Galaxy and appeared last year with the rest of the film’s primary cast at San Diego Comic Con. There are conflicting reports whether he will have any part in AAOU, but it’s likely that he will make a small appearance to further the Infinity War build-up.

Avengers: Age of Ultron premieres in theaters in North America on May 1st, 2015.