1. Buck (voiced by Nathan Fillion; Serenity, FireFly; Captain)
Buck is the leader of the Rookie’s squad from Halo 3: ODST. He is voiced by Nathan Fillion who describes Buck as “hardened† and “cranky†. Buck will also have a love interest story that will develop throughout the game.

2. Dare (voiced by Tricia Helfer; Battlestar Galactica; Number 6)
The first female soldier main character in a Halo videogame. This ODST character wears Recon Armor instead of standard ODST Armor. She is modeled and voiced by Tricia Helfer.

3. Dutch (voiced by Adam Baldwin; Serenity, Firefly; Crew)
Dutch is the Heavy Weapons specialist of Halo 3: ODST. He is also a deeply spiritual person.

4. Mickey (voiced by Alan Tudyk; Serenity, FireFly; Pilot)
Mickey is a young, enthusiastic soldier who loves the fight, but has never seen the Covenant destroy an entire planet . . .

Thought that was pretty neat.  I was playing, and saw their faces, and recognized the voices too...