These are all the current classes you can get.

Class	How to unlock
Acolyte	Purchase from Juvania in Trainers (/join trainers). Requires Healer Rank 5.
Assassin	Mazumi's Shop (/join greenguardwest) Require Ninja Rank 5 and all of her quests completed
Bard	Jon Jett (/join mythsong) Requires Rank 4 Mythsong
Beast Warrior	Ragnar's Shop, Upgrade Only (A shop in Battleon)
Berserker	Ragnar's Shop, Ugrade Only/Thok's Upgrade Shop
Card Clasher	Purchase the AQWorlds Card Game (www.heromart.com)
Chaos Shaper	Having a total of 15 months membership purchased
Defender	If you purchased any of the memberships above, you unlock Defender in the same shop
DoomKnight	Purchase from Dusk (/join shadowfall) Requires Warrior/Warlord Rank 10 and Healer/Acolyte Rank 10 and Evil Rank 5/above
DragonLord	Verify your membership in DragonFable
DragonSlayer	Complete of Galanoth's (/join lair) Quests
Elemental Dragomancer	Get rank ten in Etherstorm.
Enforcer	Drops from Mithril Man (/join dwakel)
Evolved ClawSuit 11	Frostval Gift Boxes
Evolved Shaman	Requires Arcangrove Rank 10 however, on the 29th July, 2011 if you had Arcangrove Rank 10 it would have been added to your backpack
Guardian	Verify your membership in Adventure Quest
Healer	Character Creation/Purchase from Juvania in Trainers (/join trainers)
Mage	Character Creation/Purchase from Arcana in Trainers (/join trainers)
Member-Only Classes	These are Member-Only classes you can get in AQWorlds
Necromancer	Requires NUE Necromicon and Creature Shard than merge them in the Tower of Necromancy
Necromancer	Requires NUE Necromicon and Creature Shard then merge them in the Tower of Necromancy
Necromancer	free code
Ninja	Mazumi's (/join greenguardwest) Shop
No Class	If your Membership expired this class is automatically equipped
Other Classes	These Classes are not member, or do not require you to purchase/complete anything out-of-game
Paladin	Purchase from Artix (/join swordhave)Requires Warrior/Warlord Rank 10 and Healer/Acolyte Rank 10 and Good Rank 5/above
Pirate	Complete Elisa Keenhaul's (/join pirates) last quest/Purchase it from her shop
Ranger	Requires Rank 10 Sandsea
Ranger	Rquires Rank 10 Sandsea
Renegade	Purchase from Metrea in Trainers (/join trainers). Requires Rogue Rank 5.
Rogue	Character Creation/Purchase from Metrea in Trainers (/join trainers)
Rustbucket	Complete Tarvarya's (/join dwakel) Quest, ProtoSartorium Parts
Shadow Death Master	Purchase it from Galanoth for 1000 gold
Shaman	Requires Rank 10 Arcangrove
Sorcerer	Purchase from Arcana in Trainers (/join trainers). Requires Mage Rank 5.
Special Offer Classes	These Classes can be obtained by purchasing/achieving a certain item/requirement
Star Captain	Verify your membership in Mech Quest
Starting Classes	You can either purchase these classes for 1000 gold or start with them in the Character Creation page
Tier Two Classes	These classes can be obtained by having two classes at certain Ranks.
Undead Slayer	Lady Speedstyx (/join lightguard) Requires DoomWood Rank 10
Upgrade Classes	These classes can be purchased from the NPC's above, but you need the classes above Rank 5 or higher
Vindicator Of They	Collect 90 Token of Vindication from kid Drakath daily quest in TMBG event (/join collection) or buy it for 2000 ACs
Vindicator Of They	Collect 90 Token of Vindication from kid Drakath daily quest in TMBG event (/join collection)or buy it for 2000 ACs
Vindicator of they	Collect 90 Token of Vindication from kid Drakath daily quest in TMBG event (/join collection)or buy it for 2000 ACs
Warlord	Purchase from Thok in Trainers (/join trainers). Requires Warrior Rank 5.
Warrior	Character Creation/Purchase from Thok in Trainers (/join trainers)