Armor customization (Halo 3)/Spartan

Spartan armor
Armor	Helmet	Chest	Shoulders
Mark VI	Unlocked by default	Unlocked by default	Unlocked by default
CQB	Unlocked by default	Unlocked by default	Unlocked by default
EVA	Complete the entire Halo 3 campaign on Normal difficulty or higher (Campaign Complete: Normal)	Beat Tsavo Highway on Normal difficulty or higher (The Road)	Beat The Ark on Normal difficulty or higher (Refuge)
EOD	Complete the entire Halo 3 campaign on Legendary difficulty (Campaign Complete: Legendary)	Beat Tsavo Highway on Legendary difficulty	Beat The Ark on Legendary difficulty
HAYABUSA	Collect all 13 skulls	Collect 5 skulls	Collect 9 skulls
Scout	Unlock the Used Car Salesman achievement	Unlock the Too Close to the Sun achievement	Unlock the Mongoose Mowdown achievement
Recon	Be granted the Recon armour by Bungie (2007-2009) Complete all Vidmaster Challenges in Halo 3 and Halo 3: ODST (September 2009-March 2012) Unlocked for all Halo 3 players in two waves by 343 Industries (No longer attainable for new accounts)
Security	Get 1,000	N/A	Get 750
ODST	Reach the rank of Private in multiplayer (Spartan Graduate)	N/A
Mark V	Achieve the rank of Sergeant in multiplayer (UNSC Spartan)	N/A
Rogue	Reach the rank of Lieutenant in multiplayer (Spartan Officer)	N/A
Katana	N/A	Earn 49 achievements or earn 1,000	N/A
Bungie Armor ("Flaming head")	N/A	Be an employee of Bungie Studios	N/A