Balin is one of the secondary protagonists in The Hobbit and the film trilogy. He is the older brother of Dwalin and cousin of Oin and Gloin.
Balin is the second dwarf to appear at Bag End and greet Bilbo Baggins.
The Fellowship of the Ring
It is revealed that Balin led an expedition of dwarves, Ori and Oin included, to reclaim the longlost city of Moria. However he was killed by orcs and given a tomb. The Fellowship, while passing through, discovered Balin's tomb.
The Hobbit (1977)
Balin was voiced by Don Messick. Out of all the dwarves, Balin is one of the few to speak. His role remains pretty much the same in the film..
The Hobbit trilogy
In Peter Jackson's adaptation for The Hobbit, Ken Stott portrayed Balin in all three films.
Balin is one of Thorin's oldest friends and companions, and closest friends growing up (other than Dwalin). He was very fond of his brother, Dwalin, shown when they both laugh when they see each other's presence and bonk heads together. During the course of the journey, Balin forms a friendship with the company's burglar, Bilbo Baggins, and often teaches the hobbit about Dwarf culture.