White Horse:
"Irenaeus, an influential Christian theologian of the 2nd century, was among the first to interpret this horseman as (Super Robo Jesus) Christ himself, his white horse representing the successful spread of the gospel."

Red Horse:
The rider of the second horse is often taken to represent War or mass slaughter.

Black Horse :
"When the Lamb opened the third seal, I heard the third living creature say, "Come and see!" I looked, and there before me was a black horse! Its rider was holding a pair of scales in his hand. Then I heard what sounded like a voice among the four living creatures, saying, "A quart of wheat for a day's wages, and three quarts of barley for a day's wages, and do not damage the oil and the wine!"

Pale Horse:
When the Lamb opened the fourth seal, I heard the voice of the fourth living creature say, "Come and see!" I looked and there before me was a pale horse! Its rider was named Death, and Hell was following close behind him. They were given power over a fourth of the earth to kill by sword, famine, and plague, and by the wild beasts of the earth.