Pestilence was not one of the Four Horsemen of the Apocalypse. The Horsemen were, in order of appearance:
Conquest - Rides the white horse, holds a bow
War - Rides the red horse, holds a sword
Famine - Rides a black horse, holds scales
Death - Rides the pale horse, holds nothing, hell follows him
It's also worth pointing out two other interesting points:
1.) Death is the only horseman explicitly given a name. The rest are named based on their description.
2.) Famine is the only one whose appearance comes with a vocal pronouncement. Specifically, "A measure of wheat for a penny, and three measures of barley for a penny; and see thou hurt not the oil and the wine."
(I use the King James version for my quotes. I think it's prettier.)