In Norse mythology’s Ragnarok, Heimdall blows the Gjallarhorn to warn the gods. Heimdall is the watchman of the gods, stationed at the Bifröst bridge and associated with extraordinary sight and hearing.
The horn’s blast signals the approach of the final conflict. In the poem Völuspá, Heimdall is described as raising the horn, after which the gods gather for battle. The name Gjallarhorn is related to the idea of a loud or resounding sound, fitting its role as an alarm heard across the divine world.
Gjallarhorn is sometimes confused with Heimdall’s sword or with Odin’s spear Gungnir. It is a horn, not a weapon. The horn also appears in another mythic context: Heimdall drinks from Mímir’s well, and the Gjallarhorn is mentioned as an important possession kept beneath Yggdrasil in some interpretations of the Eddic poems.
Its blast is therefore both a warning and a narrative marker that Ragnarok has begun.