Mounted archery is a form of archery that involves shooting arrows while on horseback. A horse archer is a person who does mounted archery. Archery has occasionally been used from the backs of other riding animals. In large open areas, mounted archery was a highly successful technique for hunting, for protecting herds, and for war. It was a defining characteristic of the Eurasian nomads during antiquity and the medieval period, as well as the Iranian peoples such as the Alans, Sarmatians, Cimmerians, Scythians, Massagetae, Parthians, and Persians in Antiquity, and by the Hungarians, Mongols, Chinese, and Turkic peoples during the Middle Ages. The expansion of these cultures have had a great influence on other geographical regions including Eastern Europe, West Asia, and East Asia. In East Asia, horse archery came to be particularly honored in the samurai tradition of Japan, where horse archery is called Yabusame.

The term mounted archer occurs in medieval English sources to describe a soldier who rode to battle but who dismounted to shoot, similar to the later firearm-equipped dragoons. Horse archer is the term used more specifically to describe a warrior who shoots from the saddle at the gallop. Another term, "horseback archery", has crept into modern use.

Horse archery developed separately among the people of the South American pampas and the North American prairies following the introduction of domesticated horses to the continent; the Comanches were especially skilled.

Since using a bow requires the rider to let go of the reins with both hands, horse archers need superb equestrian skills if they are to shoot on the move. The natives of large grassland areas used horse archery for hunting, for protecting their herds, and for war. Horse archery was for many groups a basic survival skill, and additionally made each able-bodied man, at need, a highly mobile warrior. The buffalo hunts of the North American prairies may be the best-recorded examples of bowhunting by horse archers.

In battle, light horse archers were typically skirmishers, lightly armed missile troops capable of moving swiftly to avoid close combat or to deliver a rapid blow to the flanks or rear of the foe. Captain Robert G. Carter described the experience of facing Quanah Parker's forces: "an irregular line of swirling warriors, all rapidly moving in right and left hand circles.. while advancing, to the right or left, and as rapidly concentrating... in the centre... and their falling back in the same manner...all was most puzzling to our... veterans who had never witnessed such tactical maneuvers, or such a flexible line of skirmishers".

In the tactic of the Parthian shot the rider would retreat from the enemy while turning his upper body and shooting backward. Due to the superior speed of mounted archers, troops under attack from horse archers were unable to respond to the threat if they did not have ranged weapons of their own. Constant harassment would result in casualties, morale drop and disruption of the formation. Any attempts to charge the archers would also slow the entire army down.

An example of these tactics comes from an attack on Comanche horse archers by a group of Texas Rangers, who were saved by their muzzle-loading firearms and by a convenient terrain feature. Fifty Rangers armed with guns met about 20 Comanche hunters who were hunting buffalo and attacked them. The Comanches fled, easily keeping clear of the Rangers, for several miles across the open prairie. They led the Rangers into a stronger force of two hundred. The Rangers immediately retreated, only to discover they had committed a classic error in fighting mounted archers: the Comanches pursued in turn, able to shoot what seemed like clouds of arrows. The Rangers found a ravine where they could shoot at the Comanche from cover. The horse archers did not charge but kept the Rangers under siege until seven of them were dead or dying, whereupon the Rangers retreated but claimed victory.

Horse archers may be either light, such as Scythian, Hun, Parthian, Cuman, or Pecheneg horsemen, or heavy, such as Byzantine kavallarioi, Turkish timariots, Russian druzhina and Japanese samurai.^{[citation needed]} Heavy horse archers typically fought as formed units. Instead of harassing without ever making contact, they shot in volleys, weakening the enemy before they charged. In addition to bows, they often also carried close combat weapons, such as lances or spears. Some nations, like medieval Mongols, Hungarians and Cumans, fielded both light and heavy horse archers. In some armies, such as those of the Parthians, Palmyrans, and the Teutonic Order of Knights, the mounted troops consisted of both super-heavy troops (cataphracts and knights) without bows, and light horse archers.