As you complete the achievements, you will unlock more armor permutations and best of all, a body set which comes with a Katana to show off your awesomeness once you get all of the achievements.

Please note that some achievements require you to complete them in RANKED FREE FOR ALL PLAYLIST. This is called LONE WOLVES in the matchmaking playlists of Halo 3.

* - Those that are self-explanatory will not be explained on how to obtain them.
** - Those that require determination and luck will not be explained.

* - Campaign Complete: Normal
Completed the Campaign on Normal difficulty.

* - Campaign Complete: Heroic
Completed the Campaign on Heroic difficulty. (Unlocks above as well)

* - Campaign Complete: Legendary
Finish the Campaign on Legendary difficulty. (Unlocks previous two as well)

- Graduate
Graduated from basic training. Stick with it to earn your Spartan Insignia. Win five ranked multi player matches.

- UNSC Spartan
Promoted to Sergeant. Proven in combat, you are a Spartan. Win twenty ranked multi player matches.

- Spartan Officer
Advance to the Spartan Officer ranks. Win seventy ranked multi player matches with a skill level of at least ten.

- Lee R Wilson Memorial
Scored 5 grenade sticks in any ranked free for all playlist. Concentrate on obtaining plasma grenades or spike grenades in the map. Know where they spawn and rush there every time. Then, concentrate on getting close to an enemy and try
your hardest to stick them with the grenade. Do this in Lone Wolves so you don't make your team mates mad while you storm the enemy base and throwing grenades. :p

- We're in for some Chop
Destroyed an enemy vehicle with equipment in a ranked playlist or in campaign. Begin on Rally Point Alpha on the level 'Tsavo Highway' on easy. Once you kill the first Wraith, proceed to kill all the Marines...yes...in this case it's alright. In the top bunker should be three trip mines. In the next area should be three Brute Choppers. Destroy one Chopper, kill the driver on the second Chopper and ignore the third. Once this is done, walk ahead to get a check point. Then get in one Chopper and slightly damage it. Then get off and wait for it to charge at you. Deploy your Trip Mine and win.

- Too Close to the Sun
Destroyed a banshee with the Spartan Laser or missile pod in a ranked playlist or in campaign. Start on easy on the level 'Cortana'. Once you destroy the anti-air Wraith, go a little further and you'll see Banshees fly over head. Next to the crash pelican should be a second Spartan Laser. Win.

** - Triple Kill
Killed 3 enemies within 4 seconds of one another in a ranked free for all playlist.

** - Overkill
Kill 4 enemies within 4 seconds of one another in a ranked free for all playlist.

** - Two for One
Scored a Double Kill with a single Spartan Laser shot in a ranked free for all playlist.

- Headshot Honcho
Killed 10 enemies with headshots in a ranked free for all playlist or in campaign. Start on easy on the level 'The Ark'. More win to follow seeing on how you start with a sniper rifle.

* - Up Close and Personal
Killed 5 enemies by melee or assassination in a ranked free for all playlist.

** - Killing Frenzy
Kill 10 enemies without dying in any ranked free for all playlist.

** - Mongoose Mowdown
Splatter an enemy with the mongoose in a ranked free for all playlist.

** - Steppin' Razor
Score a Triple Kill with the sword in a ranked free for all playlist.

** - Fear the Pink Mist
Kill 5 enemies with the needler in a ranked free for all playlist or in campaign.

** - Maybe Next Time Buddy
Board the same vehicle within 10 seconds after being boarded in any free for all playlist. You know...I was sooo close to doing this when one of my team mates betrayed me...>=(

- Used Car Salesman
Destroyed a vehicle that has three enemies in it in a ranked playlist or in campaign. Crows Nest, easy. Once you get to the hanger, take a turret and destroy the front gun of a Phantom. Not sure why this works...but it does.

* - MVP
Earned the MVP in a ranked playlist.

* - Marathon Man
Locate and access all Terminals in the Campaign.

* - Landfall
Completed the first mission of the Campaign.

* - Holdout
Completed the second mission of the Campaign.

* - The Road
Completed the third mission of the Campaign.

* - Assault
Completed the fourth mission of the Campaign.

* - Cleansing
Completed the fifth mission of the Campaign.

* - Refuge
Completed the sixth mission of the Campaign.

* - Last Stand
Completed the seventh mission of the Campaign.

* - The Key
Completed the eighth mission of the Campaign.

* - Return
Completed the final mission of the Campaign.