Watchman of the rainbow bridge, the gods’ sentinel
The sentinel guarding Bifröst, the rainbow bridge that joins the realm of the gods to that of humans. His eyes see across the nine worlds, his ears hear wool growing and grass breaking the soil, and his sleep is lighter than a bird’s. He holds the horn Gjallarhorn, to be blown at one moment only — when Ragnarök comes and the enemy host bears down. He and Loki are fated foes, and the two will slay each other in the final battle.
Heimdall watches over the nine worlds, waiting for one thing: when the host of giants and the dead crosses Bifröst toward Asgard, he will blow the Gjallarhorn, its sound shaking the nine worlds, waking the sleeping gods and the honored dead of Valhalla to meet the fated final battle.
Below are how modern works borrow or reinterpret this name or story — not the original material. The two differ, so keep them apart.