Loki is the second son of Odin, All-Father of the Asgardians. However,
Loki is not an actual Asgardian, nor the natural born child of Odin and his wife Frigga. It is ultimately revealed that he is actually a Frost Giant of Jötunheim, the mortal enemies of Asgard.
Aside from the Asgardian royal family (Odin, Frigga, Thor and Loki) who else is aware of the unusual circumstances of his parentage?
Note: I am looking for both a canon comics answer, as well as an MCU answer (if one actually does exist... which I doubt... yet).