Note that after you unlock the second subclass for one character, it will be unlocked for any new character of the same class that you make in the future.
Striker
Defender
Sunbreaker
Sunbreaker is a rumored Titan subclass that will come with The Taken King. Crusader utilizes Solar abilities.
Gunslinger
Gunslinger is a Hunter subclass that players start off with. Gunslinger utilizes Solar abilities.
Bladedancer
Bladedancer is a Hunter subclass that players unlock at level 15. Bladedancer utilizes Arc abilities.
Nightstalker
Nightstalker is a rumored Hunter subclass that will come with The Taken King. Trapper utilizes Void abilities.
Voidwalker
Voidwalker is a Warlock subclass that players start off with. Voidwalker utilizes Void abilities.
Sunsinger
Sunsinger is a Warlock subclass that players unlock at level 15. Sunsinger utilizes Solar abilities.
Stormcaller
Stormcaller is a rumored Warlock subclass that will come with The Taken King. Arc Thrower utilizes Arc abilities.