Well, the following characters will be playable in Super Smash Bros. Brawl on the Nintendo Wii, which are new to the series:

Pit (Kid Icarus)
Solid Snake (Metal Gear series)
Wario
Meta Knight (Kirby series)
Zero Suit Samus (Metroid: Zero Mission)

Who else do you think would fit in this game?

If they had a few more Fire Emblem characters, that would be awesome.