Eikþyrnir (Old Norse "oak-thorny"), or Eikthyrnir, is a stag which stands upon Valhalla in Norse mythology. The following is related in the Gylfaginning section of Snorri Sturluson's Prose Edda after the description of Heiðrún. Brodeur follows the text of the T manuscript of the Prose Edda in putting the stag í Valhöll, "in Valhall", rather than á Valhöll, "upon Valhall", as the other manuscripts do. The more recent translation by Anthony Faulkes puts the stag on top of the building, which seems much more natural from the context and weight of the evidence.