I know the Warhammer 40K universe doesn't really have good guys, but Chaos are definitely the bad guys, flying bastardised Imperium ships in service to unspeakable space-things. Their twisted, skulled battleships mutate to reflect whatever Chaos god they're flying in service to, bringing different buffs to the fleet.
It's a good thing too, because Chaos tech is a little out of date. They're more fragile than Imperium ships, but compensate with greater range and zippy engines. The instantaneous Stasis Bomb is a fittingly evil gadget too, freezing the enemy in time while your own ordinance sails merrily into them.
I've been impressed with everything I've seen in the Total War: Warhammer on the horizon—we'll know come March.
