Contains Spoilers!!!
There are over 9000 characters in the Super Smash Bros Brawl Roster, some with alternate forms (marked with an *) They are the following:
Newcomers
Pit
Wario
Ike
Pokémon Trainer*
Diddy Kong
Meta Knight
Snake
Lucas
Sonic
King Dedede
Pikmin and Olimar
Veteran Fighters
Mario
Link
Kirby
Pikachu
Fox
Samus*
Zelda*
Bowser
Donkey Kong
Ice Climbers
Yoshi
Peach
Secret Characters
Ness
Luigi
Ganondorf
Toon Link (Wind Waker Link)
R.O.B.
Falco
Wolf
Captain Falcon
Lucario
Jigglypuff
Marth
Mr. Game & Watch
Cloud Strife
Transformations
Sheik (Zelda)
Zero Suit Samus (Samus Aran)
Ivysaur/Charizard/Squirtle (Pokémon Trainer)
Note: *Secret Characters are both new and veterans