Pale Rider - Pale Horse - The Four Horsemen of the Apocalypse.
The Pale Horse is the fourth horse of the four horsemen of the apocalypse. The pale Horse is named Death and brings with it hell.
That’s where I believe the name Pale Rider comes from. Thats the origin.
So that’s what the Preacher is.
“I looked, and there before me was a pale horse. Its rider was named Death, and Hades was following close behind him. They were given power over a fourth of the earth to kill by sword, famine and plague, and by the wild beasts of the earth”
TheCaretaker