Rev. 5
7 When he opened the fourth seal, I heard the voice of the fourth living creature say, "Come!"
8 And I saw, and behold, a pale horse, and its rider's name was Death, and Hades followed him; and they were given power over a fourth of the earth, to kill with sword and with famine and with pestilence and by wild beasts of the earth.
Hades is Zeus' brother and ruler of the underworld and the dead. He was also called Pluto - God of Wealth, because the precious metals buried deep in earth were in his realm. The name Pluto was used by both the Greeks and the Romans, and it translated into Latin as Dis - "rich." Although he was an Olympian he spent most of the time in his dark castle in the underworld. Because of his dark personality he was not especially liked by neither the gods nor the mortals, he was not however, an evil god, he was stern, unpitying and inexorable, but just. Hades ruled the underworld and therefore most often associated with death and feared by men, but he was not Death itself, the actual embodiment of Death was another god - Thanatos.
A rehash of Greek mythology believed still by the Romans. In fact the burial site where the bodies of the dead were thrown over the wall of Rome to be eaten by wild animals was called Hades. They scared and threaten little children who were misbehaving by threatening to throw them into Hades.
Now you use a verse to propose Thanatos (death) and Hades are coming to get us. Who sent them. Hades brother Zeus?
It may come as a surprise to you but death will visit us all until there is a fact of mortality. Oh by the way that forth was by the Providence of Zeus and who he himself could not enter.