A.T. Robertson Commentary Revelation 6:8

"And I saw, and behold, a pale horse: and he that sat upon him, his name was Death; and Hades followed with him. And there was given unto them authority over the fourth part of the earth, to kill with sword, and with famine, and with death, and by the wild beasts of the earth." — Revelation 6:8 (ASV)

A pale horse (ιππος χλωρος). Old adjective. Contracted from χλοερος (from χλοη, tender green grass) used of green grass (Revelation 8:7; Revelation 9:4), here for yellowish, common in both senses in old Greek, though here only in N.T. in this sense, greenish yellow. We speak of a sorrel horse, never of a green horse. Zechariah (Zechariah 6:3) uses ποικιλος (grizzled or variegated). Homer used χλωρος of the ashen colour of a face blanched by fear (pallid) and so the pale horse is a symbol of death and of terror.

His name was Death (ονομα αυτω ο θανατος). Anacoluthon in grammatical structure like that in Joh 3:1 (cf. Revelation 2:26) and common enough. Death is the name of this fourth rider (so personified) and there is with Death "his inseparable comrade, Hades (1:16; 20:13f.)" (Swete). Hades (αιδης, alpha privative, and ιδειν, to see, the unseen) is the abode of the dead, the keys of which Christ holds (Revelation 1:18).

Followed (ηκολουθε). Imperfect active of ακολουθεω, kept step with death, whether on the same horse or on another horse by his side or on foot John does not say.

Over the fourth part of the earth (επ το τεταρτον της γης). Partitive genitive γης after τεταρτον. Wider authority (εξουσια) was given to this rider than to the others, though what part of the earth is included in the fourth part is not indicated.

To kill (αποκτεινα). First aorist active infinitive of αποκτεινω, explanation of the εξουσια (authority). The four scourges of Eze 14:21 are here reproduced with instrumental εν with the inanimate things (ρομφαιαι, λιμω θανατω) and υπο for the beasts (θηριων). Death here (θανατω) seems to mean pestilence as the Hebrew does (λοιμος -- cf. λιμος famine). Cf. the "black death" for a plague.