The Hobbit: Desolation of Smaug Photo Reveals Beorn in Bear Form!

"In The Hobbit, Beorn received Gandalf, Bilbo Baggins, and the 13 Dwarves and aided them in their quest to reclaim the Dwarves' kingdom beneath Erebor, the Lonely Mountain. He was convinced of their trustworthiness after confirming their tale of encountering the Goblins of the Misty Mountains, and Gandalf's slaying of their leader, the Great Goblin. Aside from giving the group much-needed resupply and lodging after their escape from the Goblins, Beorn gave them vital information about what path to take to cross Mirkwood. As it turned out, Thorin's original plan to cross using the Old Forest Road located much further south would have led them into disaster, as the road had fallen into disrepair and become flooded near the eastern end. Instead, Beorn informed them of a secret path made by the Elves which ran east-west from Thranduil's halls at the River Running at the eastern end, all the way to a western outlet not far from Beorn's home.

Later, hearing of a vast host of Goblins on the move, Beorn arrived at the Lonely Mountain in time to strike the decisive blow in the Battle of Five Armies, in his bear form, slaying the Goblin leader, Bolg, and his bodyguards; without direction, the Goblin army scattered and were easy pickings for the other armies of Men, Elves, Dwarves, and Eagles.

In the years between the Battle of Five Armies and the War of the Ring, possibly spurred by his interaction with Thorin & Company, Beorn stopped being a recluse, and rose to become a leader of the woodmen living between the Anduin river and the fringes of Mirkwood, rallying them against the remaining Orcs in the mountains. His people were known as the Beornings, and they helped defend Thranduil's kingdom at northern Mirkwood. As stated by Glóin in The Fellowship of the Ring, the Beornings also "keep open the High Pass and the Ford of Carrock." He presumably died some time before the War of the Ring itself began, and was succeeded by his son Grimbeorn the Old.

Even though Beorn could have been dead by the time, his death is not included in the chronologies in that book's appendices."