Rev. 6: 7. And when he had opened the fourth seal, I heard the voice of the fourth beast say, Come and see.
8. And I looked, and behold a pale horse: and his name that sat on him was Death, and Hell followed with him. And power was given unto them over the fourth part of the earth, to kill with sword, and with hunger, and with death, and with the beasts of the earth.
Tom, this is where it shows the two riders of this fourth horse or fourth seal.
Death and Hell, both being Capitalized show a personification; this means this is beings called or referred to as Death and Hell. This does not mean physical death or hell, it is showing the nature of this fourth condition.