Horned Viking Helmet

Horned Viking Helmet is a Plate Helmet.

Source
This item drops from Eric "The Swift" in Uldaman. It is only available to the Horde, as this NPC is flagged as friendly to the Alliance, and can therefore not be engaged in combat.

Trivia

 * In Blizzard's first game, The Lost Vikings, Erik is known for running quickly and also bashing in walls with his helmet, which stuns him as well.