Heimdall is the guardian of the gods who will blow the Gjallarhorn if danger approaches Asgard. His senses are so acute that he can hear the grass grow and he can see to the end of the world; he can hear a leaf fall; he also requires no sleep at all. He is moreover the guardian of the Bifrost Bridge.

He was the son of nine different mothers (possibly the nine daughters of Ægir, called billow maidens) and was called the White God. His hall was called Himinbjörg (Sky Mountain) and his horse was Gulltoppr (Gold-top). Snorri Sturluson's Prose Edda relates that a kenning for sword is head of Heimdall because Heimdall was struck by a man's head and that this is treated in the poem Heimdalargaldr, a poem unfortunately no longer extant. Similarly, a kenning for head is sword of Heimdall. The meaning may lie in Heimdall also being called "ram", the weapon of a ram being its head, including the horns. Georges Dumézil (1959) suggested that this might also be why Heimdall is called White-god.