Thranduil's elk

First appearing in The Hobbit: An Unexpected Journey, the Elvenking Thranduil arrives in the Lonely Mountain astride on his elk. More elks comically appear in the game LEGO The Hobbit: The Video Game, wherein they are shown as free-roaming elks within the palace.

Its second and last appearance is during The Hobbit: The Battle of the Five Armies, when Thranduil arrives in Dale to deliver food for Bard and his people. The elk continuously accompanied the Elven-king throughout the ordeal at the gates of Erebor. It is later seen assisting Thranduil when the war broke out, using its massive antlers to trap Orcs. It is killed when an arrow pierced its head.

Trivia

 * King Thranduil's elk may have been inspired by the Megaloceros ("Irish Elk") which an extinct genus of deer. In The Desolation Of Smaug, Thranduil's throne appears to be comprised of Megaloceros antlers.