Marvel
Heroes:
1) Spider-Man (includes Scarlet Spider, Ultimate Spider-Man, Spider-Man 2099, Spider Girl skins)
2) Captain America (includes Bucky/Winter Soldier, Captain Britain, Union Jack skins)
3) Thor (includes Steel (from DC), Beta Ray Bill, Ultimate Thor, Ares skins)
4) Wolverine (include X-23, Dark Wolverine, Sabretooth skins)
5) Hulk (includes Thing, She-Hulk, Colossus, Ultimate Hulk skins)
6) Daredevil
7) Iron Man (includes War Machine, Ultimate Iron Man skins)
8) Nightcrawler (includes Blink skin)
9) Iron Fist (includes Luke Cage, Black Panther, Shang Chi, Damage (from DC) skins)
10) Jean Grey (includes Spectre (from DC) skin)
11) Storm
12) Ms. Marvel (includes Capt. Marvel, Firestar, Genis, Marvel Boy skins)
13) Scarlet Witch (includes Zatanna (from DC), Raven (from DC), Amora skins)
14) Namor (includes Stingray, Namorita skins)
15) Black Widow (includes Nick Fury, Hellcat, Ultimate Nick Fury skins)
16) Hank Pym (includes Atom (from DC), Ryan Choi (from DC), Wasp, Irredeemable Ant-Man skins)
17) Iceman (includes Ice (from DC) skin)
18) Human Torch (includes Fire (from DC), Golden Age Human Torch skins)
19) Quasar (includes Adam Warlock, Star-Lord, Phyla-Vell skins)
20) Ghost Rider (includes Ghost Rider II skin)
21) Valkyrie (includes Black Knight skin)
22) Songbird (includes Black Bolt, Banshee, Black Canary (from DC), Siryn skins)
23) Man-Thing (includes Swamp Thing skin)
24) Spider-Woman (includes Arachne skin)
DLC Heroes: Punisher, Gambit, Moon Knight, Cable
Villains:
1) Doctor Doom (includes Red Skull, Kang the Conqueror skins)
2) Magneto (includes Cosmic Boy (from DC), Polaris, Xorn skins)
3) Loki
4) Green Goblin (includes Harry Osborn skin)
5) Venom
6) Mystique (includes Rogue, Unknown Soldier (from DC), Morph skins)
7) Elektra (includes Bullseye skin)
8) Shocker (includes Static Shock (from DC) skin)
9) Black Cat (includes Catwoman (from DC), Tigra skin)
10) Ultron
11) Kingpin (includes Rhino skin)
12) Apocalypse
DLC Villains: Dr. Octopus
Assist Trophies: Silver Surfer, Jamie Madrox, Galactus, Quicksilver, MODOK, Cloak and Dagger, Moondragon, Watcher, Ant-Man (Scott Lang), Warriors Three, Fin Fang Foom, Red Ghost and the Super-Apes
Reward Trophies: Cyclops, Emma Frost, Kitty Pryde, Nova, Invisible Woman, Psylocke, Vision, Professor X, Jessica Jones, Jubilee, Howard the Duck, Mary Jane Watson, Magik, J. Jonah Jameson, Princess Powerful, Dazzler, Wiccan, Northstar, Havok, Squirrel Girl, Fantomex, Black Cat, Hulkling, Cannonball, Amadeus Cho, Speedball, Longshot, Rick Jones, Mr. Sinister, Layla Miller, Sister Grimm, Talkback, Dani Moonstar, Chamber, Justice, Arsenic, Mr. Sensitive, Zemo, Blade, Warlock, Wolfsbane, Aunt May, Bishop, M, Captain (Nextwave), Awesome Andy, Sasquatch, U-Go Girl, Strong Guy, Drax the Destroyer, Ka-Zar, Killraven, Flatman, Lockheed, Cypher, Sandman, Gravity, Pete Wisdom, Dirk Anger, Shroud, Hood, Mr. Immortal, Foggy Nelson, Medusa, Union Jack II, Stilt-Man, Morbius, Cloud 9, Cecila Reyes, Hellstorm, Hellion, Maggott, Sunfire, Frog-Man, Nomad, Guardian, Franklin Richards, Echo