Introduction
Heimdall is the watchman of the gods, stationed at the rainbow bridge Bifrost to guard against the approach of giants and other enemies of Asgard. Possessed of extraordinarily keen senses, needing less sleep than a bird and able to hear grass growing, he is one of the more unusual figures of the Norse pantheon, credited with an unparalleled and highly unusual birth.
Extraordinary senses and origin
Heimdall's eyesight and hearing are said to be so acute that he can see for great distances by day or night, and hear the growth of grass and the wool on sheep. Uniquely among the gods, he is said to have been born of nine mothers, giantesses generally identified as the daughters of the sea god Aegir, who together gave birth to him at the edge of the world.
Guardian of Bifrost
Heimdall watches from his hall Himinbjorg at the point where Bifrost, the rainbow bridge connecting Asgard to Midgard, reaches heaven, guarding against any attempt by the giants to invade the realm of the gods. He possesses a horn, the Gjallarhorn, whose blast, heard throughout all the worlds, will signal the beginning of Ragnarok.
Ragnarok
At Ragnarok, Heimdall blows the Gjallarhorn to warn the gods of the coming battle, and faces his old adversary Loki in single combat; the two are fated to kill each other in the final conflict, one of several mutually fatal duels that structure the battle's outcome.