As of July 2, 2008, there are two confirmed Diablo 3 character classes.
These classes are the Barbarian and Witch Doctor.
These are not the only characters to be in the game and we can be sure to expect more to come.
Unlike the previous games, the classes will no longer be gender bound.
This means that players[YOU!] now have the option to choose if you want to be make or female.
So you can be a Female Barbarian for example.
BARBARIAN
Barbarians are Diablo's version of World of Warcrafts warrior class.
They rely on physical strength and great force.
They are what you may call masters of physical strength and they are able to wield some of the strongest physical weapons in the game.
They are also one of few classes able to duel-wield.
Known Skills:
Cleave
The barbarian swings his weapon at his enemies with amazing force.
Ground Stomp
The Barbarian stomps the ground causing any nearby enemies to become stunned.
Leap
The Barbarian launches himself at a group of units, causing massive damage to any units near his landing zone.
Seismic Slam
The Barbarian sends out a massive shock wave that destroys anything in its path.
Whirlwind
The Barbarian quickly spends around while moving about. This causes damage to anything that gets in his way.
WITCH DOCTOR
Unlike Barbarians, Witch Doctors don't rely on strength in battles.
They use various powders, gases and magic to complete their mission.
They also have the ability to manipulate the undead and exploit the minds and bodies of their enemies.
You may call this a Rogue/Shadow Priest/Warlock combination.
Known Skills:
Firebomb
The Witch Doctor launches a firebomb that explodes and causes massive damage.
Horrify
The Witch Doctor instills fear in its enemies causing them to flee and become weaker.
Locust Swarm
The Witch Doctor summons a horde of locust that devour all that come within the Witch Doctor's way.
Mass Confusion
The Witch Doctor causes his enemies to become greatly confused, thus causing his enemies to start fighting one another.
Soul Harvest
The Witch Doctor absorbs the souls of his opponents. This ultimately causes damage to his opponents while also proving beneficial for the Witch Doctor.