Armor customization

Armor Permutations are a feature in Halo 3 and Halo 3: ODST, allowing the player to aesthetically customize their multiplayer character's armor. However, the armor you wear doesn't have any effect on gameplay; they are only cosmetic changes. This feature allows players to change their helmet, shoulders, and torso armor worn by their multiplayer avatar. They also have the option of making their armor classification either "Spartan" or "Elite".

SPARTAN Armor Permutations
There are a wide variety of SPARTAN II armor permutations, with eleven helmets, eight shoulder pieces, and eight chest pieces for a total of 5,632 different SPARTAN II armor permutations: one helmet, two shoulder pieces, and one chest piece per permutation, not including the Bungie Armour chest piece. Taking into account the Rogue, Mark V, and ODST armour, which only have helmet pieces; and Security armour, which does not have a chest piece. The HAYABUSA Project, developed alongside the MJOLNIR Project, includes the HAYABUSA and Katana permutations. Note that the "Security" armor is occassionally refered to as "Marathon" armour.

Players without XBOX Live can unlock the following armor permutations (used in local custom games):


 * Full Hayabusa armor (Campaign skull collection)
 * Full EOD armor (Legendary level completion)
 * Full EVA armor (Normal or higher level completion)
 * Security shoulder armor (750 total Halo 3 gamerscore)
 * Scout helmet and chest armor (Used Car Salesman and Too Close to the Sun achievements)

Helmets

 * Mark VI: Unlocked by default.
 * CQB: Unlocked by default.
 * EVA: Complete Campaign on Normal or higher difficulty.
 * EOD: Complete Campaign on Legendary difficulty.
 * Hayabusa: Collect all 13 different Skulls in Campaign.
 * Security: Earn 1000 gamerscore in total from Halo 3 achievements.
 * ODST: Complete the Spartan Graduate achievement. (In the new rank progression system) - Reach the rank of Private Grade 2 in any playlist ranking.
 * Mark V: Complete the UNSC Spartan achievement. (In the new rank progression system) - Reach the rank of Sergeant in any playlist ranking.
 * Rogue: Complete the Spartan Officer achievement. (In the new rank progression system) - Reach the rank of Lieutenant in any playlist ranking.
 * Recon: One way is to complete all of the Vidmaster achievements in Halo 3 and Halo 3: ODST. The armor can also be unlocked by achieving something that makes Bungie feel you deserve it, such as a Forge map, film / screenshot or winning against Bungie in a Bungie VS World event.
 * Scout: Complete the Used Car Salesman achievement.

Shoulder Pieces

 * Mark VI: Unlocked by default.
 * CQB: Unlocked by default.
 * EVA: Complete The Ark in Campaign on Normal or higher difficulty.
 * EOD: Complete The Ark in Campaign on Legendary difficulty.
 * Hayabusa: Collect 9 different skulls in Campaign.
 * Security: Earn 750 gamerscore in total from Halo 3 achievements.
 * Scout: Complete the Mongoose Mowdown achievement.
 * Recon: One way is to complete all of the Vidmaster achievements in Halo 3 and Halo 3: ODST. The armor can also be unlocked by achieving something that makes Bungie feel you deserve it, such as a Forge map, film / screenshot or winning against Bungie in a Bungie VS World Event.

Chest Armor

 * Mark VI: Unlocked by default.
 * CQB: Unlocked by default.
 * EVA: Complete Tsavo Highway in Campaign on Normal or higher difficulty.
 * EOD: Complete Tsavo Highway in Campaign on Legendary difficulty.
 * Hayabusa: Collect 5 different skulls in Campaign.
 * Katana (Add-On): Complete 49 achievements of 79 in Halo 3. NOTE: There are reports from people who apparently get the armor with fewer achievements. Since the release of the mythic map pack the Katana seems to unlock for those that download early (without the need for 1000 gamerscore OR 49 achievements)
 * Scout: Complete the Too Close to the Sun achievement, although has been reported that it sometimes may appear later on.
 * Recon: One way is to complete all of the Vidmaster achievements in Halo 3 and Halo 3: ODST. The armor can also be unlocked by achieving something that makes Bungie feel you deserve it, such as a Forge map, film / screenshot or winning against Bungie in a Bungie VS World Event.
 * Bungie: A popular misconception is that the Bungie Flaming Helmet is actually a helmet mostly perceived as Hayabusa, but in fact, it is a piece of fire on the collar. Thus, it is a chest piece. It is the Bungie Chest Piece that allows the flame on the head which can be used with any helmet and shoulder piece. The only way to get it is to get hired at Bungie.

Sangheili/Elite Armor Permutations
There are a wide variety of Elite armor permutations, with 5 helmets, 5 shoulder pieces, and 5 chest pieces for a total of 15 different Sangheili armor permutations: one helmet, two shoulder pieces, and chest piece per permutation and 625 possible combinations with all pieces in consideration.

The armor pieces obtainable by players without XBOX LIVE:

Full Combat Harness: Default Full Assault Armor: Default Full Flight Armor: Complete Campaign on Heroic or above (All other armor permutations for Sangheili armor are only obtainable from XBOX LIVE)

Helmets

 * Combat: Unlocked by default.
 * Assault: Unlocked by default.
 * Flight: Unlock either Campaign Complete: Heroic or Campaign Complete: Legendary Achievements.
 * Ascetic: Unlock the Steppin' Razor achievement.
 * Commando: Unlock the Overkill Achievement.

Shoulder Pieces

 * Combat: Unlocked by default.
 * Assault: Unlocked by default.
 * Flight: Complete the level The Ark on Heroic or Legendary difficulties.
 * Ascetic: Unlock the Overkill achievement.
 * Commando: Unlock the We're in for some Chop achievement.

Chest Armor

 * Combat: Unlocked by default.
 * Assault: Unlocked by default.
 * Flight: Complete the level Tsavo Highway on Heroic or Legendary difficulties.
 * Ascetic: Unlock the Up Close and Personal achievement.
 * Commando: Unlock the Triple Kill achievement.

ODST Permutations


As seen in the ViDocs, one could use helmets from any member in the The Squad. Alternatively, they could choose not to wear a helmet, and instead copy the face from a member in the Squad.

If they pre-ordered a copy of Halo 3: ODST, they could also choose to play as Sergeant Major Avery Johnson.

Trivia

 * There was originally going to be an Arbiter Armor Permutation, but it was taken out before Halo 3's release. Bungie, however, did not explain why.
 * The neck of an Elite (regardless what armor permutation used) is completely immune to any form of damage except for a charged Type-25 Directed Energy Pistol. In addition, the projectile will simply pass through the neck, as though the neck wasn't there, without even a blood spatter. This is because both Elites and Spartans share the same hitbox (i.e. where you can hit the character), but have different models.
 * Each Elite also has a modified neck, whether sleek black, or a different model such as scale-like plating at the back.