Light spoilers, considering that these three movies are based on one book and a handful of inter-connected source material. In that sense, all that can be fully spoiled is how things look.
Which is why we’re so greatful to TheOneRing.net for picking up on some French fan-site goodness:
The Goblin King is a huge, grotesquely bloated monster that in the years of his tyrannical rule over the miserable inhabitants of the Goblin town grew fat and flabby. The Goblin town is a collection of skew-whiff ramshackle huts deep in the caves of the Misty Mountains. He commands a bunch of foul, polluted, with scars and ulcers studded goblins.
Basically, they are bandits, they live by what they can pick up from passengers on the passes through the mountains. The Goblin King and his followers manage to capture Bilbo and the dwarves. The Goblin King is more wily and smarter than it seems. He takes pleasure in torturing his prisoners — he almost succeeds to finish off Thorin Oakenshield and his companions.
Australian actor Barry Humphries has been cast as the Great Goblin in the Hobbit films, and via the previously mentioned French fan site, we have been treated to some art of what Peter Jackson’s version of this character will look like:
And one of his Goblin minions.
And a OneRing.Net forum user was sharp-eyed enough to pull this seemingly confirming still from one of the early ‘Hobbit’ video blogs:
Creepy AND Neat!