Robert Downey Jr. as Tony Stark/Iron Man
Billionare philanthropist and armored avenger who is yet to expand his superhero life as a spy working against terrorist organizations like the Ten Rings and while Robert Downey Jr is on debate to reprising his role as Iron Man for the 4th film, hope has it that he will take on the real Mandarin in this film
Sean Penn as Mandarin (Real Mandarin of the Ten Rings)
While his real name is still a mystery, the Mandarin of the Ten Rings who is yet to be confirmed accurately and properly with ten magic rings of an alternate power source that deviates from the comics in Iron Man 4. While on the subject to try without the chinese stereotypes, Marvel Studios president Kevin Feige will make sure that the character uses magic rings this time because last time when he chose to deny the rings and rip the fans off with Extremis powered Aldrich Killian, he totally made problems very irritating and worst. So now thanks to the one shot titled All Hail the King for having Killian debunked from being the MCU version of the Mandarin and that the character's true MCU version, the leader of the Ten Rings is still live and at large , hopefully he will have the Mandarin properly reintroduced as the magic ring blaster we totally favor so much for the fourth Iron Man film and when he does, the best actor that would fit the role as Tony's true arch enemy Mandarin without the chinese stereotypes is Sean Penn. Sean Penn may not be chinese or from the Middle East, but what suits him for the role as the characters proper Marvel Cinematic Version is not only does his facial image ressemble the Mandarin in the comics but he also resembles Ben Kingsley and his voice sounds just like the Mandarin in the first half of Iron Man 3 which would help show a supporting reason to why Aldrich Killian had Trevor Slattery created as the Mandarin we saw in Iron Man 3 and because Sean is 17 years younger than Kingsley, he should be capable of putting up a real good fight against Downey but surely if they do reintroduce the Mandarin properly with 10 magic rings this time for the James Bond plot inspired fourth film, there are sure to be plenty of steps that Kevin Feige and the Marvel Studios will be sure to take in order for that to happen while they are sure to still try without most of the character's chinese stereotypes, without spoiling the character's appearance on height and gender, without screwing him up again like they did in Iron Man 3 and not only will they need to have the powers of those rings done but also some magic based battle armor just like the one from Armored Adventures so that his battle with those rings against Iron Man look more reasonably realistic as well.
Don Cheadle as Col. James Rhodes/War Machine/Iron Patriot
Tony's best friend who occasionally helps him as War Machine/Iron Patriot will be sure to help him out on his mission to stop the Ten Rings.
Gwyneth Paltrow as Pepper Potts
Tony Stark's former assistant and girlfriend whose role in the movie is yet to be revealed
Michael Shannon as Ghost
An enemy of Iron Man with stealth technology, gadgets and martial arts skills that makes him a highly trained and very deadly assassin. In Iron Man 4 he will serve as the Mandarin's top hitman in the Ten Rings organization.
Evangeline Lilly as Wasp
While waiting confirmation for Lilly to be the Janet Pym/Wasp (as Hank Pym's daughter), Lilly was mentioned to make multiple film appearances in the Marvel Cinematic Universe and as Wasp, her powers would make her a very suitable ally for Tony on his Bond like scouting missions in the film.
Paul Bettany as the Vision
With Paul Bettany confirmed to play the Vision in the Avengers Age of Ultron movie next year speculating that his original voice over character in the MCU Jarvis becomes the android, his computer/IT network interfacing, intangibility and molecular disruption powers would definately make him a very reliable ally to Tony on his mission in the film
Kim Kardashian as Sunset Bain
With Iron Man 4 planned as a James Bond like film, it does need women too like Kim Kardashian as Sunset Bain. Whether she'll be a villainess or a supporting character depends on what Marvel has in store for her.
Selena Gomez as Sasha (Mandarin's Daughter)
If there is anyway for Marvel Studios to ensure that the Mandarin will not be spoiled on his physical appearance and not get screwed up again like the last time in Iron Man 3, it would be to have someone included to help Iron Man convince the Mandarin to give up his life of sinister world domination after the armored avenger defeats him if he the real Mandarin is a real human being who gets the ten magic rings from a specific source of magic. Someone close to him like his daughter Sasha. In the comics, Sasha is the daughter of both the Mandarin and Justine Hammer who works with them in their sinister operations against Iron Man. But if she is introduced in the Marvel Cinematic Universe along with her father without the asian ethnicity, she wouldn't be a part of her father's sinister terrorist organization. She would appear as a normal and civilized human being hanging out with some friends
Ty Sympkins as Harley
Jon Favreau as Happy Hogan
Ben Kingsley as Trevor Slattery (the fake but also failed Mandarin)
Jackson Norris(Member of the Ten Rings loyal to the Mandarin)
stay tuned for future updates on the film