Hades

Hades, Greek god Death and ruler of the Underworld of Hades.
He speaks through the mouth of those that speak to him.
A distant member of The Olympians.
First appeared in Season 2.
==Season 2==
Hades was present at Fionn's birthday party during Halloween 1985, alongside the Olympic Pantheon, dressed as a ghost in a white sheet. He was a constant, if dispassionate, observer during the party.
He stayed neutral in the conflict between Erebus, Zeus and Fionn until the death of Apollo awoke in him visions of how terrible things could turn out for the Olympians.
He visited, and schooled, Fionn Corvin as the Ghost of Christmas Future during Christmas 1985. Without speaking he presented one of his visions of a future that might come; the asphyxiation of the Olympians in Olympus.
==Season 5==
Challenged Kal Eckstein, as part of Calliope's Seven Trials of Baddassery for Kal, to a game of chicken on the Devil's Elbow. Kal survived the crash.
Emerged that he took Eddie Eckstein from his death in the explosion at the wreckage of Kal's childhood home in Anchorage to his realm in the Underworld of Hades. Kal journed to Hades by drowning himself off the coast of Clearwater and was snatched out of death by Hades to his realm. However Kal was tethered to Asgard by Sigrun's lengthy Golden Thread which kept one foot out of his grave. Kal travelled for 28 days through the barren, desloate grey wastes until he reached Hade's Palace of Bones; a sepulchral-like cathedral.
Kal met Hades, who sat neutrally in his throne beside his kidnapped consort-bride Persephone.  Kal threw his two coins into Hade's urn-jar and Hades spoke (through Kal) to him about being robbed of his death-debt as Kal had survived his earlier surely fatal head-on collision on the Devil's Elbow. Now that he had him he swore to never let him leave. For what it was worth Hades told Kal that Eddie was now resident in a new addition in his realm which Persephone had insisted he construct. Persephone secreted a message to Kal of the location of this part of his domain and Kal left, his golden thread undetected.