For Halo: CE movie:
Master Chief- get some really tall guy in a suit and have Steve Downes do the voice again
Captain Keyes- Ed Harris
Cortana- Catherine Zeta Jones
Sgt. Johnson- Denzel Washington
343 Guilty Spark (voice only)- Anthony Daniels
Halo 2/3 additional:
Prophet of Regret (voice only)- Harrison Ford
Prophet of Mercy (voice only)- Christopher Walken
Prophet of Truth (voice only)- William Defoe
The Arbiter (voice only)- Keith David
Admiral Hood- Anthony Hopkins
Miranda Keyes- Evangeline Lily
Master Chief- get some really tall guy in a suit and have Steve Downes do the voice again
Captain Keyes- Ed Harris
Cortana- Catherine Zeta Jones
Sgt. Johnson- Denzel Washington
343 Guilty Spark (voice only)- Anthony Daniels
Halo 2/3 additional:
Prophet of Regret (voice only)- Harrison Ford
Prophet of Mercy (voice only)- Christopher Walken
Prophet of Truth (voice only)- William Defoe
The Arbiter (voice only)- Keith David
Admiral Hood- Anthony Hopkins
Miranda Keyes- Evangeline Lily