The Four Horsemen of the Apocalypse are figures mentioned in the Biblical Book of Revelation. The Book of Revelation, written by John of Patmos, is the most difficult book of the Bible, and there is much controversy over what exactly it is — literal or allegorical, a prophecy of the future or a commentary on current events. In any case, the Book of Revelation is full of rich and mysterious imagery, including the Four Horsemen, which have inspired the imagination and speculation of Christians and others into the modern day.
The Book of Revelation describes the Four Horsemen of the Apocalypse as part of the mysterious events revealed to the author in a lengthy vision that makes up the bulk of the text. Each of the Four Horsemen has a different colored horse and an attribute which suggests his character. The last of the Four Horsemen is named in the Bible as Death, but the identities of the others are less clear. Popularly, the four are often called Pestilence, War, Famine, and Death, though this interpretation is not universally accepted. The Four Horsemen are often interpreted as an allegory of the harbingers of the end of the world.
The first Horseman is the rider of a white horse, carries a bow, and wears a crown. He is described as a conqueror. For this reason, he is sometimes interpreted as the Antichrist or as a false world leader. This Horseman is also sometimes called Pestilence.
The second Horseman is astride a red horse and carries a sword. He is associated with war and slaughter, and the Bible attributes to him the power to take away peace and to make men kill each other.
The third Horseman rides a black horse and carries scales. This Horseman, popularly called Famine, is thought to represent not only scarcity of food, but also the strict rationing or unfair allocation of goods and the exploitation of the poor. The last of the Four Horsemen, Death, rides a "pale horse" of a sickly hue and is followed by Hades, or Hell.
The nature of the Four Horsemen of the Apocalypse is hotly debated by theologians and Christians, but they are almost universally fascinating, regardless or perhaps because of their mystery. They were popular subjects for art during the medieval period and the Renaissance, and references to them continue to crop up in popular culture in our own day and age. Whether or not Pestilence, War, Famine, and Death are the correct interpretations of the Biblical Four Horsemen -- which will likely remain in debate for the foreseeable future -- it is safe to assume that that is what they represent in a cultural or literary context.