For those wondering about the unusual names, Tolkein based all the dwarf names on the Old Norse poem "Völuspá," which was piece primarily concerning Norse mythology. All the dwarves in Tolkein's novel enjoy music, and each knows how to play an instrument.
Thorin Oakenshield (Richard Armitage), son of Thráin, son of Thrór, King under the Mountain.
The leader of the the company of dwarves, Thorin comes from the royal Durin line of dwarves. Oakenshield is actually a nickname, referencing Thorin's use of an oak branch as both a shield and sword while defending the underground city of Moria (as seen in The Lord of the Rings trilogy) from Orcs. As a young man, Thorin saw the destruction of the dwarf kingdom of Erebor and has long sought to seek revenge on Smaug and reclaim his people's wealth.
We're sure Thorin will get plenty of heroic moments in the movie, particularly during the Battle of Five Armies, which should occur in the third installment, 2014's There and Back Again, as The Battle of Five Armies was almost the title (the second chapter is 2013's The Hobbit: The Desolation of Smaug, to clear up any confusion). Tolkien purists will note that the cinematic Thorin lacks a long beard (Thorin's clan is known as the Longbeards, after all), but Thorin is slightly taller than most of the other dwarves, as described.
Bombur (Stephen Hunter), brother of Bofur and cousin of Bifur.
Basically, the "fat one." That isn't meant as an insult, Tolkein's first description of Bombur is that he is "immensely fat and heavy," and the poster has him stuffing his face with a plate of food in his hands proves that Jackson isn't thinking any differently. Usually hungry or sleepy at all times and last wherever he goes, Bombur is the comic relief of the group. Expect pratfalls. Lots of pratfalls.
Dori (Mark Hadlow), brother of Ori and Nori.
The eldest of the three brothers, Dori is thought to be one the stronger dwarfs, and is therefore often forced to carry Bilbo around at various stages, much to his dismay, as he doesn't always hold on to him very well. Particularly in the Misty Mountains. But don't worry, Dori doesn't blame himself. Besides, he helps Bilbo out plenty during their quest.
Nori (Jed Brophy), brother of Ori and Dori.
Loyal to his brothers, no one ever really knows what Nori is up to, as older brother Dori is usually looking after the youngest, Ori (classic middle-child syndrome). Nori is likely on the quest to avoid trouble with the authorities of his dwarvish home (expect Jackson to take comedic advantage of this). Still, in the book at least, Nori does help Bilbo out during an attack from the Wargs (wolf-like creature).
Dwalin (Graham McTavish), brother of Balin and a relative of Thorin.
Tolkien fans will note the lack of a blue beard tucked into a gold belt, but hopefully still has a cloak and hood to lend Bilbo for their journey. Clearly the most conscientious of the group, Dwalin is the first dwarf to arrive at Bilbo's door at Bag End. Dwalin also notices the lack of Thorin after a clash with a group of spiders and suggests that Bilbo uses his ring at a critical moment.
Fili (Dean O'Gorman), brother of Kili and nephew of Thorin.
Fili and Kili are the youngest of the dwarves, and have grown up under the stern command of his uncle. Fili has the keenest eyes in the group, which helps him find dangerous caves along the Misty Mountains and a key entrance to Lonely Mountain. Both of the brothers have relatively substantial roles in the book and are some of the more active character during the journey, likely because of the training they received by their uncle.
Balin (Ken Stott), brother of Dwalin and relative of Thorin.
The second eldest dwarf behind Thorin, Balin lived in Lonely Mountain prior to Smaug's destruction. Balin accompanied Thorin's father, Thráin, on a journey wherein Thráin was lost in the Mirkwood and captured by the Necromancer (i.e. Suaron, or the evil eye in the Lord of the Rings movies). An old warrior, Balin seems the wisest of the group, and becomes a confidante to Bilbo. In the extra scenes from the recent trailer, Balin tells Bilbo the truth about his sword, which has not yet been named Sting.
Balin does appear in The Lord of the Rings: The Fellowship of the Ring as well, but only as a corpse. Balin and a group of dwarves tried to recolonize Moria, which didn't go so well when Balin was felled by Orcs. The Fellowship come across his tomb before encountering a group of Orcs themselves.
Ori (Adam Brown), brother of Dori and Nori.
The youngest of the three brothers, Ori gets short shrift in the book, but is clearly educated and becomes a dwarf historian, as he is the one who writes about Balin's death in the Book of Mazarbul, and then tells of their own dark end, the final entry reading: "They are coming." Don't feel bad, though, dwarves live for hundreds of years!
Óin (John Callen), brother of Glóin and a distant cousin of Thorin.
Along with his brother, Óin is in charge of starting the fire, which never happens as easily as it probably could. Still, when Bilbo needs a torch to investigate Smaug's chamber, Óin is there to help out. Along with Balin and Ori, Óin is one of the dwarves that returns to Moria prior to the events of The Fellowship of the Ring, but, unlike the other two, he was not killed by Orcs. Instead, the Watcher in the Water (the giant, octopus-like creature in the water outside the gate to Moria) killed him instead.
Glóin (Peter Hambleton), brother of Óin, and a distant cousin of Thorin.
Like Bombur, Glóin is married (to a female dwarf with a fine beard) and is the father of Gimli, the dwarf from the Lord of the Rings movies (played by John Rhys-Davies). Like his prickly son, Glóin is not easily impressed and is the least convinced of Bilbo in the beginning. Glóin actually appears in Fellowship of the Ring at the Council of Elrond in Rivendell, where he was again played by Rhys-Davies.
Kili (Aidan Turner), brother of Fili and nephew of Thorin.
Kili and his brother Fili are the youngest members of the dwarf company, nad haven't ventured very far in Middle Earth. While both Kili and Fili are supposed to have blonde beards, Kili is dark-haired, a choice likely made to help differentiate the two brothers. Both Kili and Fili get plenty of attention in Tolkein's novel and are known for their cheery attitudes and skill throughout their adventure. Both will also play key roles during the Battle of Five Armies.
Bofur (James Nesbitt), brother of Bombur and cousin of Bifur.
Like his brother and cousin, Bofur is not related to Thorin in any way, and is likely on the journey for the thrill of it (and the potential for gold, of course). He will also be discernible amongst the dwarves for Nesbitt's Irish accent, and his proximity to Bombur. While more physically capable, the two are often together. In the extra scenes from the second trailer, Bofur clarifies the "incineration clause" in Bilbo's contract.
Bifur (William Kircher), cousin to Bombur and Bofur.
Like his cousins, Bifur is not from Thorin's royal lineage and is instead descended from miners and iron workers. In the movie, Bifur is rendered mostly inaudible due to a axe to the head and instead communicates with grunts and hand gestures. A loyal cousin, Bifur is on the lookout for Bombur and Bofur, and how Bifur will tell the rest of the company when his cousins end up in trouble will likely be a humorously tense situation. Bifur is also not afraid to take on Trolls.