The Avengers: Earth's Mightiest Heroes: Civil War (Season 4)

In a battle between Nitro and the New Warriors, Nitro exploded, seemingly killing the entire team and a huge number of civilians (including 60 school children nearby). This led the United States government to introduce a "Living Weapon of Mass Destruction" registry for all super-powered individuals. Most heroes were divided on the issue, and a Civil War ensued within the Avengers.

Registered Heroes and Villains:

 * Natasha Romanoff/Black Widow (Vanessa Marshall)
 * Doc Samson (Cam Clarke)
 * Tony Stark/Iron Man (Eric Loomis)
 * Reed Richards/Mr. Fantastic (Dee Bradley Baker)
 * Carol Danvers/Ms. Marvel (Jennifer Hale)
 * A.G. Bell/Phone Ranger (Daniel Riordan)
 * Jennifer Walters/She-Hulk (Ashley Tisdale)
 * Greer Grant/Tigra (Alyson Stoner)
 * Thor Clone/Ragnarok (Rick D. Wasserman)
 * Janet Van Dyne/Wasp (Colleen O’Shaughnessey)
 * Hank Pym/Yellowjacket (Wally Wingert)
 * Simon Williams/Wonder Man (Phil LaMarr)
 * Lucas Bishop (Kevin Michael Richardson)
 * Scott Wright/Micromax (Max Mittleman)
 * Ruph Bat-Seraph/Sabra (Jim Meskimen)
 * Robert Baldwin/Penance (Peter Dobson) - previously Speedball, registered
 * Melissa Gold/Songbird (Gabrielle Union)
 * Great Lakes Champions:
 * Doreen Green/Squirrel Girl (Nancy Cartwright)
 * Tippy Joe (Frank Welker)
 * Craig Hollis/Mr. Immortal (Marc Worden)
 * Val Ventura/Flatman (Adrian Padsar))
 * Ashley Crawford/Big Bertha (Diane DeLano)
 * DeMarr Davis/Doorman (Jason Spiziak)
 * Robert Reynolds/Sentry (Crispin Freeman)
 * Patricia Walker/Hellcat (Hynden Walch)
 * Thor Girl (Andrea Baker)
 * Matthew Hawk/Two-Gun Kid (Phil Morris)
 * Anya Corazon/Araña (Grey Griffin)
 * John Jameson (Adam Baldwin)
 * Cassie Lang/Stature (Colleen O'Shaughnessey)
 * Kyle Richmond/Nighthawk (\Adam Adamwaite)

S.H.I.E.L.D. Forces:

 * Director Maria Hill (Kari Wuhrer)
 * Dum Dum Dugan (John DiMaggio)
 * Sharon Carter/Agent 13 (Danika McKeller)
 * Agent Whitman (Wally Kurth) - sent by Iron Man to capture Luke Cage
 * Gabe Jones (Diedrich Bader)
 * Superhuman Restraint Unit/Cape-Killers

Enforcers:

 * Wade Wilson/Deadpool (Nolan North)
 * Eric Brooks/Blade (T.C. Carson)
 * Heroes for Hire:
 * Colleen Wing (Kari Wahlgren)
 * Misty Knight (Anika Noni Rose)
 * Maria Vasquez/Tarantula II (Maria Canals)
 * Shang-Chi (Daniel Wu)
 * Buck Mitty/Humbug (Billy West)
 * Orka (David Boat)
 * Felicia Hardy/Black Cat (Jessica DiCicco)
 * Paul Dennings/Paladin (Greg Ellis)
 * Thunderbolts:
 * Noh-Varr (Andre Braugher)
 * Noh-Varr (Andre Braugher)

Detained and recruited heroes and villains:

 * Ajaxis (Peter Dobson) - villain, a member of the Thunderbolts Army
 * Peter van Sante/Aqueduct (Liem O'Brien) - villain, a member of the Thunderbolts Army
 * Marco Scarlotti/Whiplash (Vincent Tong) - villain
 * Eric Conroy/Bloodstrike (Peter Lurie) - villain, a member of the Thunderbolts Army
 * Batroc the Leaper (Rene Auberjoinis)
 * The Beetles: members of the Thunderbolts Army
 * Joaquim Robichaux (Carlos Alazraqui)
 * Elizabeth Quinn (Danika McKeller)
 * Gary Quinn (Dee Bradley Baker)
 * Fred Myers/Boomerang (Steven Blum) - a member of the Thunderbolts Army
 * Lester/Bullseye (Jon Curry) - a member of the Thunderbolts Army
 * Quincy McElver/Bushmaster (David Oyelewo) - a member of the Thunderbolts Army
 * Otto Octavius/Doctor Octopus (Corey Burton) - a member of the Thunderbolts Army
 * Eddie Lavell/Eel (Neil Kaplan)
 * Norman Osborn/Green Goblin (Kevin Michael Richardson) - a member of the Thunderbolts Army
 * Melina Vostokoff/Iron Maiden (E.G. Dailey) - a member of the Thunderbolts Army
 * Steven Levins/Jack O'Lantern (Marc Worden) - a member of the Thunderbolts Army
 * Jonathan Powers/Jester (Piotr Michel)
 * Simon Maddicks/Killer Shrike (Robin Atkin Downes)
 * Yuriko Oyama/Lady Deathstrike (Kelly Hu) - a member of the Thunderbolts Army
 * Mariano Lopez/Machete (Danny Trejo) - a member of the Thunderbolts Army
 * Mongoose (James Sie) - a member of the Thunderbolts Army
 * Grom/Over-Mind (Richard McGonagle) - a member of the Thunderbolts Army
 * Raymond Bloch/Ox (Bill Fagerbakke) - a member of the Thunderbolts Army
 * Alex Gentry/Porcupine (Ted Levin)
 * Psionex:
 * Heidi P. Franklin/Pretty Persuasions (???)
 * James Sharp/Coronary (???)
 * Thomas Sorenson/Mathemanic (???)
 * Dwight Hubbard/Impulse (???)
 * Quicksand (???) - Asian female, a member of the Thunderbolts Army
 * SJ3RX/Red Ronin (???) - a member of the Thunderbolts Army
 * Ebeneezer Laughton/Scarecrow (???) - a member of the Thunderbolts Army
 * Serpent Society:
 * Roland Burroughs/Death Adder
 * Klaus Voorhees/King Cobra (James C. Mathis III) - also a member of the Thunderbolts Army
 * Gustav Krueger/Rattler (Chris Cox) - also a member of the Thunderbolts Army
 * Min Li Ng/Silk Fever (???) - a member of the Thunderbolts Army
 * Jalome Beacher/Slyde (???) - a member of the Thunderbolts Army
 * Conrad Mack/Smiling Tiger (???) - a member of the Thunderbolts Army
 * Snake Marston (???) - a member of the Thunderbolts Army
 * Tony Masters/Taskmaster (???) - a member of the Thunderbolts Army
 * Arnold Paffenroth/Tatterdemalion (???)
 * Drew Daniels/Texas Twister (???)
 * U-Foes:
 * Simon Utrecht/Vector (Cam Clarke) - also a member of the Thunderbolts Army
 * Michael Steel/Ironclad - also a member of the Thunderbolts Army
 * Ann Darnell/Vapor (Colleen O'Shaughnessey) - also a member of the Thunderbolts Army
 * Jimmy Darnell/X-Ray - also a member of the Thunderbolts Army
 * Milos Masaryk/Unicorn (???)
 * Eddie Brock/Venom (???) - a member of the Thunderbolts Army
 * Edward Wheelan/Vermin (???)
 * Whiplash (???) - the female version and a member of the Thunderbolts Army
 * Dave Cannon/Whirlwind (???) - a member of the Thunderbolts Army
 * Wrecking Crew:
 * Dirk Garthwaite/Wrecker (JB Blanc)
 * Brian Calusky/Piledriver (Nolan North)
 * Henry Camp/Bulldozer (James C. Mathis III)
 * Elliot Franklin/Thunderball (Gary Anthony Williams)
 * Maximillian Zaran (???) - a member of the Thunderbolts Army

Major Government Supporters:

 * Dallas Riordan/Vantage (???)
 * Henry Peter Gyrich (Jim Ward)
 * Valerie Cooper (???)

Major Civillian Supporters:

 * Happy Hogan (???)
 * J. Jonah Jameson (J.K. Simmons)
 * Miriam Sharpe (???)
 * Sprite (???) - trickster from Olympus

The Secret Avengers:

 * Julia Carpenter/Arachne (???) - formerly upheld the act
 * Nathaniel Summers/Cable (???)
 * Luke Cage (Christopher B. Duncan)
 * Steve Rogers/Captain America (Brian Bloom)
 * Piotr Rasputin/Colossus (Nolan North)
 * Scott Summers/Cyclops (Nolan North)
 * Alex Summers/Havok (Nolan North)
 * Rachel Leighton/Diamondback (???)
 * T'Challa/Black Panther (James C. Mathis III)
 * Ororo Munroe/Storm (Susan Dalian)
 * Tyrone Johnson/Cloak (???)
 * Tandy Bowen/Dagger (???)
 * Jessica Drew/Spider-Woman (???)
 * Matt Murdock/Daredevil (???)
 * Danny Rand/Iron Fist (Loren Lester)
 * Sam Wilson/Falcon (Lance Reddick)
 * James Howlett Logan/Wolverine (Steve Blum)
 * Bill Foster/Goliath (???)
 * Jane Foster (Kari Wahlgren)
 * Nick Fury (Alex Desert)
 * Hercules (???)
 * Linda Carter/Night Nurse (???)
 * Young Avengers:
 * Eli Bradley/Patriot (Khary Payton)
 * Billy Kaplan/Wiccan (Jesse McCartney)
 * Teddy Altman/Hulkling (Nolan North)
 * Cassie Lang/Stature (Colleen O'Shaughnessey) - later registered
 * Kate Bishop/Hawkeye (Stephanie Lemelin)
 * Thomas Shepherd/Speed (Jason Spisak)
 * Vision (Peter Jessop)
 * Tsu-Zana/Ultragirl (???)
 * Delroy Garrett, Jr./Triathlon (???)
 * Miguel Santos/Living Lightning (???)
 * Susan Storm/Invisible Woman (Erin Torpey) - formerly upheld the act as a member of the Fantastic Four
 * Johnny Storm/Human Torch (David Kaufman) - formerly upheld the act as a member of the Fantastic Four
 * Silhoutte Cord (???)
 * Bonita Juarez/Firebird (???)
 * X-51/Machine Man (???)
 * Monica Rambeau/Photon (???)
 * Peter Parker/Spider-Man (Josh Keaton) - formerly supported the act
 * Vance Astrovik/Justice (???)
 * Walter Newell/Stingray (???)

Miscellaneous heroes and villains:

 * Lemar Hoskins/Battlestar (???)
 * Eric Savin/Coldblood (???)
 * Jack Harrison/Jack Flagg (???)
 * Johnny Blaze/Ghost Rider (???)
 * Robin Braxton/Gladiatrix (???) and her resistance cell
 * Obax Majid/Lightbright (???)
 * N'Kantu the Living Mummy (???)
 * Sarah Vale/Network (???)
 * Richard Gilmore/Prodigy (???)
 * Hobie Brown/Prowler (???)
 * Maximillian Coleridge/Shroud (???)
 * James Bourne/Solo (???)
 * Robert Baldwin/Speedball (found alive, registered change into Penance)
 * Gordon Thomas/Typeface (???)
 * Jonathan Bryant/Digitek (???)
 * Thomas Samuels/Lectronn (???)
 * Maria de Guadalupe Santiago/Silverclaw (???)

Unregistered heroes and villains:

 * Deborah Fields/Debrii (???)
 * Angelica Jones/Firestar (???)
 * Jessica Jones (???)
 * Frank Castle/Punisher (???)
 * Erik Lehnsherr/Magneto (Tom Kane)
 * Pietro Maximoff/Quicksilver (Mark Hildreth)
 * Elvin Haliday/Rage (???)
 * Runaways:
 * Alex Wilder (???)
 * Nico Minoru (???)
 * Karolina Dean (???)
 * Molly Hayes (???)
 * Chase Stein (???)
 * Gert Yorkes (???)
 * Old Lace (???)
 * Steven Harmon/Slapstick (???)
 * Stanley Johnson/Thunderclap (???)
 * Rina Patel/Timeslip (???)
 * Sersei (???)
 * Marc Spector/Moon Knight (???)
 * Howard the Duck (???)
 * Bucky Barnes/Winter Soldier (Jon Curry)

Registered Opponents:

 * Julia Carpenter/Arachne (???) - formerly upheld the act, now a Secret Avenger
 * Susan Storm/Invisible Woman (Erin Torpey) - formerly upheld the act, now a Secret Avenger
 * Peter Parker/Spider-Man (Josh Keaton) - formerly upheld the act, now a Secret Avenger
 * X-Factor Investigations:
 * Jamie Madrox/Multiple Man (Crispin Freeman)
 * Guido Carosella/Strong Guy (???)
 * Rahne Sinclair/Wolfsbane (???)
 * 198:
 * Maximus Jensen/Mammomax
 * Erg
 * Fever Pitch
 * John Zander/Jazz
 * Xi'an Coy Manh/Karma
 * Lorelei Travis
 * Peter Quinn/Peepers
 * Mortimer Toynbee/Toad
 * Inez Temple/Outlaw
 * Johnny Dee
 * Sack
 * Sally Blevins/Skids
 * Philippa Sontag/Arclight
 * Caliban
 * Leech
 * Han, Chang, Lin, Sun, and Ho Tao-Yu/Collective Man
 * Lillian Crawley/Diamond Li
 * Beautiful Dreamer
 * Manuel de la Rocha/Empath
 * Several unidentified/unidentifiable mutants

Supervillain opponents:

 * Matthew Gilden/Goldbug (???)
 * Edger Plunder/Plunderer (???)
 * Wilson Fisk/Kingpin (???)
 * Robert Hunter/Nitro (Liam O'Brien)

Major civilian opponents:

 * Citizens of Harlem, New York
 * Neil Crawford (???)
 * Sally Floyd (???)
 * Yancy Street Gang

Foreign opponents:

 * Blackbolt - Inhuman King of the Royal Family
 * Namor

Neutral parties:

 * Stephen Strange/Doctor Strange (???)
 * Ben Grimm/Thing (Clancy Brown) - formerly upheld the act as a member of the Fantastic Four)
 * Ben Urich (???)
 * Thena (???) and most of the other Eternals
 * X-Men (publicly):
 * Charles Xavier/Professor X (Jim Ward)
 * Jean Grey (Jennifer Hale)
 * Anna-Marie D'Ancanto/Rogue (Kieren van din Blink)
 * Kurt Wagner/Nightcrawler (Liam O'Brien)
 * Hank McCoy/Beast (Fred Tatasciore)
 * Kitty Pryde/Shadowcat (Danielle Judovits)
 * Bobby Drakes/Iceman (Yuri Lowenthal)
 * Jonathon Silvercloud/Forge (Roger Craig Smith)
 * Remy LaBeau/Gambit (Phil LaMarr)
 * Richard Rider/Nova (???)
 * Thor (Rick D. Wasserman)

Casualties:

 * 600 residents of Stamford, CT
 * Roberto Velasquez/Bantam (???) - killed in a fight with Thunderclap
 * Bill Foster/Goliath (???) - killed in a fight with Thor
 * Cee (???) of the Yancy Street Gang
 * Ralph Roberts/Cobalt Man (???) - killed at Stamford
 * Kateri Deseronto/Coldheart - killed at Stamford
 * John Fernandez (???)
 * Matthew Gilden/Goldbug (???) - killed by Punisher
 * Johnny Storm/Human Torch (David Kaufman) - severely wounded by anti-hero protestors
 * Zachary Smith, Jr./Microbe (???) - killed at Stamford
 * Namorita Printiss (???) - killed at Stamford
 * Edger Plunder/Plunderer (???) - killed by Punisher
 * Sheila Blake/Speedfreak (???) - killed at Stamford
 * Jalome Beacher/Slyde (???) - killed by Jack Dio/Underworld
 * Dwayne Taylor/Night Thrasher (???) - killed at Stamford
 * Jonathan Powers/Jester (???) - killed by Punisher
 * Steven Levins/Jack o' Lantern (???) - killed by Punisher
 * Superhuman Restraint Unit

Trivia:

 * The season takes plot elements from Marvel: Ultimate Alliance 2 and Captain America: Civil War.