A buckler (French bouclier 'shield', from Old French bocle, boucle 'boss') is a small shield, up to 45 cm (up to 18 in) in diameter, gripped in the fist with a central handle behind the boss. While being used in Europe since antiquity, it became more common as a companion weapon in hand-to-hand combat during the Medieval and Renaissance periods. Its size made it poor protection against missile weapons (e.g., arrows) but useful in deflecting the blow of an opponent's weapons, binding his arms, hindering his movements, or punching him.

MS I.33, considered the earliest extant armed-combat manual, (around 1300) contains an early description of a system of combat with buckler and sword.