A horse archer was a cavalryman whose primary weapon was a bow. Horse archers shot while riding, as opposed to mounted archers who merely used their horses for transport. Because using a bow from a running horse required a horseman to let go of the reins with both hands, horse archers needed superb equestrian skills. Horse archery is therefore typically associated with steppe nomads.

Horse archers could be very efficient because their combination of ranged weapons and speed allowed them to kill without retaliation. Therefore horse archers usually won from both infantry and heavy cavalry. A famous tactic was the Parthian shot, feigning a retreat and then shooting rearwards at a pursuing foe. The weapon of choice for horse archers was the composite bow, a bow with horn and sinew for added tensile strength, because it was compact enough to shoot from a horse and retained sufficient range and penetrating power. Because horse archers could avoid direct contact with an adversary they needed little or no armour and could ride on ponies. After the invention of the stirrup, horse archers would stand up in their stirrups to absorb the movement of the horse and increase their accuracy.

Horse archers played a pivotal role in the battles of Carrhae and Liegnitz.