The Barbarian was the first Diablo III character class to be revealed, and was unveiled at the 2008 Blizzard Worldwide Invitational in Paris, on 28 June, 2008.
Originally, although the character class was intended to share similar traits with the Barbarian character class from Diablo II, it wasn't intended for the Barbarian class to return, as Jay Wilson (Game Director for Diablo III) explained in a 2008 GDC interview with AusGamers:
"The barbarian is the only returning class. Originally we actually planned to have no returning classes, but as we developed the Barbarian, it essentially ended up turning into a Barbarian. We sort of got to the point where we went – because we actually had a different name for him originally - I think we're going to call it this other name and everyone else is just going to call it the Barbarian, so maybe we should just call it the Barbarian." Jay Wilson
One of the most notable changes made to the class since Diablo II is the replacement of Mana with Fury. Fury is a resource that represents pure anger and battle-lust. Instead of a globe of energy that needs refilling, a Barbarian's Fury orb will start off empty and fill as he/she takes or deals damage, this can then in turn be used to cast Barbarian skills. There are, however, some skills that require no fury or actually generate fury, so the Barbarian can nonetheless initiate battle. If you stop fighting, after a short grace period, your fury will slowly recede.
Barbarian Fury orb.
However, most of the Barbarian's original traits remain in-tact: he is still focussed on strength and pure power, and as such the Fury resource system offers much better synergy than the traditional Mana pool. He is also still an expert in melee combat and mastery, and is able to wield enormous weapons and heavy shields. And the War Cry system of old is still a key aspect of the class.