Dwalin is one of the secondary protagonists in The Hobbit and in The Hobbit film trilogy. In the trilogy, he is portrayed by Graham McTavish.
Dwalin was born in TA 2774 and was the brother of Balin and son of Fundin and the cousin of Óin and Glóin He was one of the 12 Dwarves accompanying his friend and King, Thorin Oakenshield to reclaim their homeland from the dragon Smaug, later joined by their hired Hobbit 'burglar' Bilbo Baggins.
After the Battle of the Five Armies, Dwalin lived in Erebor until he died of old age.
Sir Peter Jackson's films
The Hobbit: An Unexpected Journey
Dwalin was the first dwarf to come to Bilbo's door. The dwarf introduced himself and bowed to the Hobbit. Gandalf asked why Thorin is not among them and Dwalin answers that he is late because of a meeting in Ered Luin with their kin. After Thorin arrives, Dwalin inquired if Dáin is with them, but Thorin says they will not come. He was like all the other dwarves who thought Bilbo was not going to survive in the Wild for being too soft. The former just proves this by saying that gentlefolk can't defend themselves.
When Bilbo is captured by trolls, Dwalin with the others rescue Bilbo. After all of the dwarves are put into sacks for the trolls to eat later, he was on the spit over the fire. Luckily thanks to Bilbo and Gandalf's interferences, the Trolls all turn to stone. When the Troll hoard is discovered Dwalin accompanied Thorin, Gandalf and a couple of dwarves invade it. His cousin, Bofur, and Nori bury treasure, which Dwalin scuffs in disgust.
During the chase, Dwalin killed a warg with his axes. In Rivendell, after Kíli's flirting with an elf, and also on another elf, Dwalin is aware it is a male and not a female, saying that it was not an Elf maiden that Kíli looked at. And he also throws food around when Bofur's singing "The Man in the Moon" song. In the Misty Mountains, after Thorin had saved Bilbo, Dwalin helped Thorin come back to the Mountain. The company is captured by Goblins while Bilbo escaped and Dwalin fights well while escaping with the others and the Great Goblin's carcass landing on the broken dwarves.
Even though the dwarves and Bilbo escaped the Goblin Tunnels, Azog the Defiler finally cornered the Dwarves out of the forest. The trees start to fall, and Dwalin hoplessly watches as Thorin is crushed until Bilbo himself leaps up and saves Thorin. Dwalin eventually regains his footing and rushes in to defend Bilbo and Thorin's unconscious body along with Fili and Kili. The eagles finally come and the Company escapes Azog the Defiler
The Desolation of Smaug
Dwalin is seen next to Thorin, and asks a returning Bilbo if the Wargs picked up their scent, which they hadn't done yet. All of them are driven to no other choice but to run to Beorn's house, travel through Mirkwood. In Mirkwood, Dwalin looses all of his possessions, especially his weapons. Bilbo eventually saves them and lets them escape.
Dwalin openly distrusts Bard and suggests that they throw the human over board and take his boat by force. Thorin confides that he knows that Bard is untrustworthy to Dwalin. He also calls Bard a traitor as Bilbo spies on him. Dwalin is the first dwarf to enter through the toilet and the plumbing system and Threatens to rip of Bain's arms if he speaks of this to anyone.
After Bilbo, Balin and Thorin discuss the day Smaug attacked, Bain says that his ancestor broken the scale off of the left breast, but Dwalin dismisses it as a myth. Their company is later brought before the master of Laketown, where Dwalin stood up to the Master and presented Thorin as "This is Thorin, son of Thráin, son of Thrór. He was one of Thorin's remaining companions who traveled to the Lonely Mountain (Thorin, Bilbo, Balin, Dori, Nori, Ori, Bifur, Bombur, and Glóin were the additional members also not staying behind.)
When Bilbo awakens Smaug, Thorin rushes in to rescue their friend. Afterwards, Dwalin along with the other dwarves storm in to Bilbo's and Thorin's rescue before being chased by Smaug in different directions.
The Battle of the Five Armies
Dwalin is first seen hugging his friends that returned from Laketown. Next he is seen with his brother Balin at his side, the dwarf king looking at the broken throne, and Bilbo standing behind/next to Thorin. The brothers reports to Thorin that the Arkenstone has not been found, and even yells it. He spotted the Laketown survivors streaming into Dale and putting up a fortress by Thorin's orders.
Thorin also any one of the dwarves are holding the Arkenstone in his possession. The friend Dwalin once knew was gone when Thorin attacked Bilbo, and Dwalin and Fíli tries to protect him from Thorin's wrath.
Even when he tells Thorin that Dáin is surrounded and that they are failing the war, Thorin shows no sign of pity. Dwalin accuses Thorin of not being of who he once was and that he isn't the friend he once knew. The former threatens to kill his own friend if he does not leave. After Thorin broke from madness, Dwalin fallowed his friend to end this with Fíli and Kíli, and Bilbo fallowing to warn them.
Bilbo eventually completed it. Dwalin wants to engage Azog now, but Thorin says it's not wise and that they'll "live to fight another day." He ordered for Dwalin to retrieve Fíli and Kíli while Thorin would lead Bilbo out of Ravenhill. Fíli is revealed to be captured by Azog and his band of Orcs, and Dwalin watches along with Thorin, Bilbo, and Kíli as Fili dies and is dropped dead in front of his own brother. He apparently is nowhere to be seen after that, but when the Goblin missionaries attack Bilbo, Dwalin rushes in to defend the Hobbit and Bilbo assisting him until he was knocked out.
After Bilbo discovered Thorin's dead body, Dwalin is shown mourning for his best friend. He later says goodbye to Bilbo and smiles but also cries, as he leaves. Bilbo then tells Dwalin that he can eat him out fo food whenever he comes in and visits.