What/who have commentators historically believed the "four riders" of Revelation 6 were?
The following is a couple of historical perspectives from the literature. (These are not theological perspectives).
The first historical perspective is that the 4 riders of Revelation 6 were according to the article Four Horsemen of the Apocalypse (This article also has many links at its end):
The first Horseman is represented by the Anti-Christ, who
The second Horseman, or red Horseman represents conflict and whose arrival
The third or black Horseman, represents famine and disease, which according to the article:
the final Horseman, is Death, with the goal
The article uses the example of the Middle Ages, where famine, plague and war ravaged Europe, leading many to believe that the Apocalypse was upon them.
Digging a little deeper, for a second historical perspective, as to the possible influences that inspired the descriptions of the Four Riders, according to a brief article Albrecht Durer’s “The Four Horsemen of the Apocalypse” (Hanna, 2010), based on a late 15th century illustrated book about Revelation 6 by Albrecht Durer who illustrated the following representation of the 4 Riders:
an interpretation (not necessarily my interpretation) is the first Horseman were portrayed as Ottoman Turk cavalrymen (archer) who went and conquered Constantinople, then one of the greatest cities of Christendom.
The second horseman was represented as contemporary German mercenaries of the age about when Revelations was written (the one with the sword), these mercenaries were also known as the Landsknecht. These are an example that Durer used to represent those who made war.
The third horseman is interpreted by Durer as being those who had control over the food stores at the time of Revelation's writing (represented by the scales), which according to Hanna:
Finally, the final Horseman, is interpreted by Durer as being the culmination of all the previous wrongdoings and
(Hopefully, I am answering this question correctly):