The Hobbit features thirteen dwarves that make up Thorin Oakenshield's company:

Fili and Kili--These two brothers are the youngest in the company.  Thorin is their uncle; he is their mother's eldest brother.  Fili and Kili both are killed in the Battle of the Five Armies defending Thorin with "shield and body" (261).

Bifur and Bofur-- Bifur and Bofur are brothers and were descended from the dwarves of Moria but were not of Durin's line. 

Bombur-- Bombur is the fattest of the dwarves.  He accidentally falls into the dark river of Mirkwood and falls into an enchanted sleep. Bombur is also a brother of Bifur and Bofur.

Dwalin-- The first dwarf to appear on Bilbo's doorstep at the beginning of the story.  He and Balin are both descended from the House of Durin and are remote cousins to Thorin.

Balin--One of the oldest dwarves in the party, Balin returns with Gandalf at the end of the novel some years later to visit Bilbo at Bag-End.  He is Dwalin's brother.  Balin later goes to Moria.  His tomb is found by the Fellowship during their journey through the mountain. 

Oin--Oin is also descended from the House of Durin, so they are also distant cousins to Thorin.  He and Gloin are brothers and are first cousins to Balin and Dwalin. 

Gloin--Gloin originally doubts Bilbo's skills as a burglar, saying "he looks more like a grocer than a burglar" (18).  Gloin's statement actually goads Bilbo into wanting to join the company.  (Gloin's greatest significance is that he is Gimli's father (Gimli later becomes one of the Nine Companions in Lord of the Rings). 

Dori, Nori, Ori--All three are brothers and play the flute.  They are also of the House of Durin and are more distant kinsman of Thorin. 

Thorin--Thorin Oakenshield II is a direct descenedent of Durin.  He is the heir to the Lonely Mountain and the leader of the company of the dwarves.  Extremely proud of his heritage, Thorin's deepest desire is to rebuild the greatness of the Lonely Mountain. 

How many dwarves are in The Hobbit?

Bilbo Baggins's simple hobbit life is about to be turned upside down and inside out. He opens the door to his hobbit hole one afternoon at tea time, expecting the wizard Gandalf, and instead comes face to face with the dwarf Dwalin. Next Balin shows up, then Kili and Fili, followed by Dori, Nori, Ori, Oin, and Gloin. The final group to show contains Bifur, Bofur, Bombur, and the illustrious Thorin Oakenshield. Almost before Bilbo realizes what has happened, there are thirteen dwarves sitting around his table.

These dwarves are bent on adventure and revenge. They are setting out for the Lonely Mountain where the dragon Smaug long ago invaded their domain, capturing their treasure and killing many of their kin. The dwarves are ready to reclaim what is theirs ... with the help of the bewildered Bilbo, whom Gandalf has identified as a burglar, much to Bilbo's dismay!

Much later in the story we meet one more dwarf, Dain, Thorin's cousin, who comes down from the Iron Hills with an army of dwarves to aid his kinsman. After Thorin's death, Dain stays on as King under the Mountain.

Interestingly, Tolkien borrowed many of the dwarves' names (and Gandalf's name, too) from the Old Norse poem Völuspá. Tolkien had long been fascinated with ancient Germanic literature in Old Norse, Old English, and other ancient Germanic languages. He was also frustrated that many of the stories behind the names in these pieces were lost over the centuries, and many times, he set out to create a story to illustrate the names.