Heimdall

In Norse mythology, the god of light and sentinel of the gods. Present at the creation of the world, it was believed that he would also usher in the twilight of the gods. He guarded the frontiers of the heavens and Bifrost, the rainbow-bridge which led to Midgard (Earth), against the assaults of the giants.

As a sentry, his hearing was so acute that he could hear the grass grow, and Gjall, his warning horn, could sound throughout the Nine Worlds.

Heimdall's enemy was the disreputable god-giant Loki, who mocked Heimdall's devotion to duty, and with whom he had a feud on account of Freya's stolen necklace, Brisingamen. It was believed that they would slay each other at Ragnarök, the final battle between the gods and forces of evil.