Heimdall is an immortal being from the Grigori home world of Asgard. 

In mythology Heimdall is the watchman of the Norse gods, and he guards Bifrost, the rainbow bridge. He will blow the Gjallarhorn if danger approaches Asgard. At the final conflict of #Ragnarok he will do battle with #Loki

Heimdall is noted to his intense loyalty to Odin and his son Thor.