Beorn is described as a skinchanger who had the ability to transform from a man into a large black bear. In a wooden house between the Misty Mountains and Mirkwood he shared his dwelling with all his animals: horses, ponies, dogs, etc. In his original form Beorn was of huge size and strength with strong arms, black hair, and a beard. No one knew about Beorn’s origin, but Gandalf supposed he had come from the mountains. He grew plants and flowers, loved animals and didn’t eat them; he ate fruits, bread, honey, and cream. Beorn preferred to live like a hermit, although he was acquainted with some of the people who lived in the area not far away from his house.
That was Beorn who helped Bilbo Baggins and his companions in their quest and provided them with food and ponies to reach the forest of Mirkwood. He took part in the Battle of Five Armies in the form of a bear, saved Thorin Oakenshield from the goblins and killed Bolg, the goblins’ leader.
After the battle, Beorn returned home together with Bilbo and Gandalf and invited many people from miles around to join them in Yuletide celebration. Soon he became a leader of men, known as the Beornings, and they helped to protect Thranduil’s kingdom at northern Mirkwood.
Beorn won fame as a fair leader and died before the time of the War of the Ring. After his death, his son Grimbeorn became the leader of the Beornings.