As with the Weapons each character has their own set of armour already unlocked which is exclusive to their class. It is possible to obtain another two sets of armour by completing Crucible and Strike activities respectively. A complete set of armour will consist of a Helmet, Chest, Legs and a class specific Mark.
Hunter Armour
Unlocked: Frumious Mark, Grips, Vest, Strides (armour), Frumious Cloak (Mark).
Crucible Unlockables: Swordflight 4.1 (armour), Binary Phoenix Cloak (Mark).
Strike Unlockables: The Took Offence (armour and Mark)c.
Titan Armour
Already Unlocked: Noble Constant Type 2 (armour), Noble Constant Mark (Mark).
Crucible Unlockables: Phoenix Strife Type 0 (armour), Binary Phoenix Mark (Mark).
Strike Unlockables: The Shelter In Place (armour and Mark).
Warlock Armour
Already Unlocked: Ego Talon IV (armour), Ego Talon Mark (Mark).
Crucible Unlockables: Ankaa Seeker IV (armour), Binary Phoenix Bond (Mark).
Strike Unlockables: Xenos Vale IV (armour), Xenos Vale Bond (Mark).