The subject of this article or section originates from non-canonical sources. To find out about what is considered "canon" see LOTR:Canon.
Thranduil does not ride an elk originally in The Hobbit.
During the Battle of Five Armies, the elk seems brave, calm, and well-experienced with combat involving large numbers of foes, including smaller Orcs and Trolls. He was also marked by physical prowess and stamina to participate in a large battle without exhausting for considerable amount of time.
Portrayal in adaptations
Peter Jackson's The Hobbit trilogyDale to deliver food for Bard and his people. The elk, now older and greyer, accompanies the Elven-king throughout the ordeals at the gates of Erebor.
He is later seen assisting Thranduil when the battle breaks out around the mountain and the ruins of Dale - he uses his speed and massive antlers (while ridden) to trap, rout, and kill dozens of Orcs of the armies of Azog. The elk is eventually slain when charging into legion of orcs, shot twice with arrows in the neck and once in the head.
King Thranduil's elk may have been inspired by the Megaloceros ("Irish Elk"), a very large, prehistoric genus of deer which roamed Europe and Asia during the Pleistocene and earlier Holocene until about 7,700 years ago. In The Desolation Of Smaug, Thranduil's throne appears to be comprised of Megaloceros antlers, which are not obtained by killing their owners but by collecting them when they are naturally and seasonally shed, as with other cervine species.