who Thanatos is

In Greek mythology, Thánatos (in Greek, Θάνατος – "Death") was the daemon personification of Death. He was a minor figure in Greek mythology, often referred to but rarely appearing in person. His name is transliterated in Latin as Thanatus, but his equivalent in Roman mythology is Mors or Letus/Letum, and he is sometimes identified erroneously with Orcus (Orcus himself had a Greek equivalent in the form of Horkos, God of the Oath).
The Greek poet Hesiod established in his Theogony that Thánatos is a son of Nyx (Night) and Erebos (Darkness) and twin of Hypnos (Sleep).
"And there the children of dark Night have their dwellings, Sleep and Death, awful gods. The glowing Sun never looks upon them with his beams, neither as he goes up into heaven, nor as he comes down from heaven. And the former of them roams peacefully over the earth and the sea's broad back and is kindly to men; but the other has a heart of iron, and his spirit within him is pitiless as bronze: whomsoever of men he has once seized he holds fast: and he is hateful even to the deathless gods." [1]
Thanatos was thought of as merciless and indiscriminate, hated by - and hateful towards - mortals and the deathless gods. But in myths which feature him, Thanatos could occasionally be outwitted, a feat that the sly King Sisyphos of Korinth twice accomplished. When it came time for Sisyphos to die, he cheated Death by tricking him into his own shackles, thereby prohibiting the demise of any mortal while Thanatos was so enchained. Eventually Ares, the bloodthirsty god of war, grew frustrated with the battles he incited, since neither side suffered any casualties. He released Thanatos and handed his captor over to the god, though Sisyphos would evade Death a second time by convincing Persephone to allow him to return to his wife. As before, Sisyphos would be recaptured and sentenced to an eternity of frustration in Tartaros.

A fragment of Alcaeus, a Greek lyric poet of the 6th century BC, refers to this episode:

"King Sisyphos, son of Aiolos, wisest of men, supposed that he was master of Thanatos; but despite his cunning he crossed eddying Akheron twice at fate's command." [3]
Sisyphus, son of Aiolos was a more than mortal figure: for mortals Thanatos usually presents an inexorable fate, but he was only once successfully overpowered, by the mythical hero Herakles. Thanatos was consigned to take the soul of Alkestis, who had offered her life in exchange for the continued life of her husband, King Admetos of Pherai. Herakles was an honored guest in the House of Admetos at the time, and he offered to repay the king's hospitality by contending with Death itself for Alkestis' life. When Thanatos ascended from Hades to claim Alkestis, Herakles sprung upon the god and overpowered him, winning the right to have Alkestis revived. Thanatos fled, cheated of his quarry.

Euripides, in Alcestis:

"Thanatos : Much talk. Talking will win you nothing. All the same, the woman goes with me to Hades' house. I go to take her now, and dedicate her with my sword, for all whose hair is cut in consecration by this blade's edge are devoted to the gods below." [4]
and for those of you who have read "On a Pale Horse"
Thanatos is Zane, a young man driven by despair to the brink of suicide, whose jumpiness only gets him into a bigger mess when he unwittingly kills the Grim Reaper. In a long-standing tradition, Death's killer must assume his role, and so Zane takes on the Reaper's mantle, traveling the world on Mortis, the sometimes-horse, sometimes-car which has long been Death's steed, collecting the souls of the dead. Soon, however, he founds himself drawn up in the wicked web of none other than Satan, himself!

I thought you might like to know a bit about me.