The complete cast of Ultimate Marvel vs Capcom 3.

LINK TO IMAGES : [link]

For the Cast We Have :
Wolverine & Ryu
Iron Man & Morrigan
Hulk & Chris Redfield
Deadpool & Dante
Dormammu & Viewtiful Joe
Doctor Doom & Chun-Li
Captain America & Felicia
Super Skrull & Trish
Thor & Amaterasu
X-23 & Tron Bonne
Spider-Man & Albert Wesker
Magneto & Nathan Radd Spencer
M.O.D.O.K. & Sir Arthur
She-Hulk & Zero
Storm & Crimson Viper
Shuma Gorath & Jill Valentine
Phoenix & Mike Haggar
Taskmaster & Akuma
Sentinel & Hsien-Ko
Ghost Rider & Firebrand
Hawkeye & Strider Hiryu
Doctor Strange & Nemesis T-Type
Iron Fist & Vergil
Nova & Phoenix Wright
Rocket Raccoon & Frank West
and Galactus

UMvC3 is for Playstation 3, X-Box 360, and Playstation Vita.
As for Downloadable Content, we have Jill Valentine and Shuma Gorath. Further Character DLC hasn't been announced, or will it might ever be announced. There are however, DLC costumes.

February 15, 2011 : Costume Pack 01
Ryu as Street Fighter 1 Ryu
Dante as Sparda
Chris Redfield as S.T.A.R.S. attire
Thor as Classic Thor
Iron Man as Iron Patriot
Captain America as Steve Rogers

Comes With Jill and Shuma Gorath DLC :
Jill Valentine as Resident Evil 3 Jill
Shuma Gorath as Quoggoth

November 22, 2011 : The Rising Dead Pack
Frank West as Mega Man X
Ghost Rider as Ghost Rider 2099
Nemesis as Nemesis without his upper garments
Phoenix as Jean Grey

December 2, 2011 : The Evil Twin Pack
Deadpool as Cablepool
Hsien-Ko as Mei-Ling
Spider-Man as Scarlet Spider
Vergil as Corrupted Vergil

December 20, 2011 : The Ancient Warrior Pack
(Magneto was removed due to controversial issues.)
Arthur as Zombie Arthur
Firebrand as Red Arremer King
Hulk as World War Hulk

January 10, 2012 : The Brawler Pack
She-Hulk as Jennifer Walters
Iron Fist as Ultimate Iron Fist
Mike Haggar as Final Fight 3 attire
Spencer as Bionic Commando : ReArmed appearance

January 17, 2012 : The Femme Fatale Pack (Pre-Order)
Chun-Li as Street Fighter Alpha outfit
Morrigan as Casual outfit
X-23 as X-Men : Evolution outfit
Storm as Morlock attire

January 17, 2012 : The Villain Pack (Pre-Order)
M.O.D.O.K. as M.E.M.P.H.I.S.
Wesker as S.T.A.R.S uniform
Crimson Viper as S.I.N. outfit
Super Skrull as Annihilation attire

January 17, 2012 : The New Age of Heroes Pack (Pre-Order)
Doctor Doom as Doomwar outfit
Sentinel as Classic Sentinel
Strider Hiryu as Arcade Strider
Akuma as Cyber Akuma

January 24, 2012 : The Animal Pack
Wolverine as Weapon X
Rocket Raccoon as Original Appearance
Felicia as Yellow Iris
Amaterasu as Jon Talbain

February 7, 2012 : The Weapon Expert Pack
Zero as Mega Man X
Hawkeye as Ronin
Taskmaster as UDON Taskmaster
Trish as Gloria

February 21, 2012 : The Viewtiful Strange Pack
Tron Bonne as Servbot Head Mech
Phoenix Wright as College Clothes attire
Viewtiful Joe as Human Joe
Doctor Strange as Blue Mage
Dormammu as Classic Dormammu
Nova as Point One attire

Galactus does not have a DLC costume.