A cataphract was a form of armored heavy cavalry utilised in ancient warfare by a number of peoples in Western Eurasia and the Eurasian Steppe.

The word in English is derived from the Greek: κατάφρακτος Kataphraktos (plural: κατάφρακτοι Kataphraktoi), literally meaning "armored" or "completely enclosed". Historically, the cataphract was a very heavily armored horseman, with both the rider and steed draped from head to toe in scale armor, while typically wielding a kontos or lance as their weapon.

".. But no sooner had the first light of day appeared, than the glittering coats of mail, girt with bands of steel, and the gleaming cuirasses, seen from afar, showed that the king's forces were at hand." Ammianus Marcellinus, late Roman historian and soldier, describing the sight of Persian cataphracts approaching Roman infantry in Asia Minor, circa fourth century.

Cataphracts served as either the elite cavalry or assault force for most empires and nations that fielded them, primarily used for impetuous charges to break through infantry formations. Chronicled by many historians from the earliest days of Antiquity up until the High Middle Ages, they are believed to have given rise in part or wholly to the Age of Feudalism in Europe and the later European equivalents of Knights and Paladins, via contact with the Byzantine Empire.