Combatants' Home Series

Most of the Death Battle combatants are taken from their own home series to be pitted against other combatants (The only exceptions however who are not listed are Justin Bieber and Rebecca Black, because they are real life people), They are listed by the following series in Death Battle episode order (Note: the characters with bold letters in their name are the Death Battle Winners, and this symbol: "*" means that the character has won twice, those that are Italic mean that the combatant has fought twice or more, and those who have two "*"s are characters with undecided fates (have been confirmed for Death Battle but their episode has not been released)):

Star Wars: Boba Fett, Luke Skywalker

Metroid: Samus Aran

Street Fighter: Akuma, Zangief, Chun-Li, Blanka, M. Bison

Mortal Kombat: Shang Tsung, Raiden, Shao Kahn, Sektor**

Marvel Heroes: Rogue, Thor, Spiderman

DC Heroes: Wonder Woman, Batman, Superman

Super Mario (including Donkey Kong Country, Yoshi's Island, & WarioLand/WarioWare): Goomba, Koopa Troopa, Yoshi, Mario, Princess Peach, Luigi

Final Fight: Mike Haggar

Teenage Mutant Ninja Turtles: Leonardo*, Donatello, Michelangelo, Raphael

BattleToads: Zitz

Killer Instinct: Riptor, Black Orchid, Fulgore**

DarkStalkers: Felicia

BlazBlue: Taokaka

God of War: Kratos

Spawn: Spawn

Bomberman: Bomberman

Dig Dug: Dig Dug

Dragon Ball Z: Vegeta, Goku

Sonic the Hedgehog: Shadow the Hedgehog, Sonic the Hedgehog, Dr. Ivo "Eggman" Robotnik, Metal Sonic, Miles "Tails" Prower

Harry Potter: Harry Potter

Fatal Fury: Mai Shiranui

Transformers: Starscream

My Little Pony: Rainbow Dash

Halo: Master Chief

Doom: Doomguy

Mega Man: Dr. Albert W. Wily

Legend of Zelda: Princess Zelda, Link

Final Fantasy: Cloud Strife

Pokemon: Pikachu, Venusaur, Blastoise, Charizard

He-Man and the Masters of the Umiverse: He-Man

ThunderCats: Lion-O

Ninja Gaiden/Dead or Alive: Ryu Hayabusa

Strider: Strider Hiryu

Soul Caliber: Isabella "Ivy" Valentine

StarFox: Fox McCloud

Bucky O' Hare and the Toad Wars: Bucky O' Hare

Terminator: Terminator

Robocop: Robocop

Avatar: The Last Air Bender: Toph Beifong**

Trivia

 * When it comes to the series with the most number of Death Battle champions, it is currently known to be a 3 way tie between Street Fighter, Marvel Heroes, and Sonic the Hedgehog; each with 3 Death Battle champions (Akuma, Zangief, and Blanka from Street Fighter; Rogue, Thor, and Spiderman from Marvel Heroes; and Sonic the Hedgehog, Metal Sonic, and Miles "Tails" Prower from Sonic the Hedgehog).