A horse archer was a cavalryman whose primary weapon was a bow. Because using a bow 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.

Drawing a bow required of an archer to put weight behind his bowarm i.e standing still. Arrows however had a relatively short range and low lethality and were useless in close quarters. Foot archers were therefore highly vulnerable, especially against armoured opponents. Horse archers, with their weight resting on horseback could nock and loose arrows while moving. A famous tactic was the Parthian shot, turning away from an enemy while continuing shooting. In English the term can also apply to a particular nasty parting remark.

The weapon of choice for horse archers was the recurve bow, because it was compact enough to shoot from a horse and retained sufficient range and penetrating power. The only threat to horse archers were arrows and they could wheel away out of bowshot after every attack. They therefore needed little or no armour and could ride light mounts such as ponies. This made them cheap to equip and increased their mobility.

A drawback of horse archers was that the movements of a running horse disturbed the accuracy of the shot. After the invention of the stirrup, horse archers would stand up in their stirrups to absorb the motion of the horse. Another method to facilitate accurate shooting was to time shots between the strides of the horse.

Horse archers played a pivotal role in the battles of Carrhae and Liegnitz. In both cases horse archers won the day because their opponents depended on direct contact. Horse archers were eventually made obsolete by the development of modern firearms.