A minor controversy exists concerning the last half of verse 8: "And power was given to them over a fourth of the earth, to kill with sword, with hunger, with death, and by the beasts of the earth." The argument deals with whether this sentence applies to the fourth horseman alone or summarizes the depredations of all four. The latter seems preferable.
Jesus appears to treat the first four seals as a subgroup in His Olivet prophecy, saying of them, "All these are the beginning of sorrows" (Matthew 24:8). His intent is clear: These four judgments are a distinct set of calamities that acts as a kind of warm-up for the exceedingly more terrible judgments of the time of the end. As He warns, "See that you are not troubled; for all these things must come to pass, but the end is not yet" (verse 6). It is entirely logical to believe that the same Revelator would likewise separate the Four Horsemen from the last three seals with a short summary of their work as well as the limits of their authority.
Another proof involves the fact that the sentence restates the missions of the red ("to kill with sword"), black ("with hunger"), and pale ("with death [thánatos, meaning disease]") horsemen. Applying these means of destruction to the fourth horseman alone would make the other two redundant and significantly diminish their roles. In addition, lumping pestilence in with hunger, war, and beasts as activities of the fourth horseman would obscure the role of disease as a judgment of God.
Commentators argue that the plural pronoun "them" in Revelation 6:8 has "Death" and "Hades" as its antecedents. They are certainly the closest antecedents, but the Greek does not demand them to be the pronoun's true antecedents. Besides, the real subject of the previous sentence is not really "Death" and "Hades" but the singular "name" of the fourth horseman. If God intended it to be a summary statement of the whole passage, we can easily recognize "them" to refer to the entire passage's active characters—the Four Horsemen—the ones to whom the Lamb gave authority to execute His judgment.
A final, curious factor is the inclusion of "by the beasts of the earth" in the powers of the horsemen; it seems to come out of the blue. However, it follows naturally in the progression of catastrophes. In times of severe war, famine, and disease, depopulation occurs, which upsets the precarious balance between human civilization and wildlife. Suddenly, with hunting and developing of wilderness areas reduced or eliminated, the population of predatory creatures expands, increasing the chances of animal attacks on humans.
The Bible provides an example of this in Genesis 10:8-9. It is thought that Nimrod's rise to power over the post-Flood world began with his skills in hunting and killing predators, which had the upper hand over the miniscule human population at the time. Another example appears in Exodus 23:29, in which God promises Israel, "I will not drive [the Canaanites] out from before you in one year, lest the land become too desolate and the beasts of the field become too numerous for you" (see also Deuteronomy 7:22; Ezekiel 34:25, 28). Incursions of lions actually killed some Samaritans after Assyria took the bulk of the Israelites into captivity (II Kings 17:25).
Wild beasts are included in the curses for disobedience of Leviticus 26: "I will also send wild beasts among you, which shall rob you of your children, destroy your livestock, and make you few in number; and your highways shall be desolate" (verse 22; see Deuteronomy 32:24; Jeremiah 15:3; Ezekiel 14:15). Through Ezekiel, God prophesies that disasters such as the Four Horsemen bring happen together with the scourge of wild beasts: "So I will send against you famine and wild beasts, and they will bereave you. Pestilence and blood shall pass through you, and I will bring the sword against you. I, the LORD, have spoken" (Ezekiel 5:17; see 14:21; 33:27). Though death by wild beasts is included in the text of Revelation 6:8 without warning, it fits nonetheless.