So this is my barbarian build, i think many people might want to have a barbarian since there's no barbarian companion in the game. It's focused on high melee dps and it'll outdo most other classes in terms of dps when you're below %50 HP.
Race: Human Meadow Folk (extra dps when your health is low, aumaua or dwarf are also good choices if you want different stats)
Stats: 18 Might 18 constitution 16 dexterity 7 perception 12 intellect 7 resolve
You may want to increase offensive stats even more, but it'll cost you deflection, so go ahead and increase them if you have a good tank in your party with high engagement limit and/or you're a good tactician when it comes to positioning.
Culture: Doesn't matter since you can adjust the stats no matter which culture you choose, but if you want a score like 19 or even 20 pick accordingly.
Background: Slave (we need athletics and survival skills)
Gear: A good light or medium armor and two weapons, an item that gives you immunity to critical hits, as your deflection will be low. You will have high endurance and hp so no worries if you position yourself well. Two handed weapons if you don't care about Carnage as Carnage works better when you have fast attacks.
Abilities (in order):
Frenzy: A must have for dps, when upgraded it gives you +6 might and constitution and %33 attack speed bonus.
Blooded: Double damage when your endurance is below %50, this is huge.
Brute Force: Your attacks can target the enemy's fortitude if it is lower, giving you a great accuracy bonus when synergized with Threatening Presence.
Threatening Presence: Makes the enemies near you sick. It's mainly a large fortitude debuff, synergises really well with Brute Force talent. With these two talents you make up for Barbarian's low starting accuracy, increasing your damage output by a large amount.
Vengeful Defeat: You attack everyone around you when going down. Those hits will have all the bonuses that you get when you have -%50 endurance. Ouch. If some healer gets you up and you go down again it will trigger once more. Fun times...
Heart of Fury: 1/rest you attack everyone around you with a large bonus damage. Another fun and effective ability, but you might take another one if you don't like that 1/rest part.
Greater Frenzy: Upgrades your Frenzy ability.
Two Weapon Style (%20 attack speed bonus, making your already high attack speed even higher)
Barbaric Blow: An aoe attack with high damage, high crit chance and extra crit damage. 1/encounter. Yes please.
The other talents are up to you, I just listed the really good class talents.