A gladius (gladius hispaniensis, the spanish sword) is a short sword, 60cm long, used by the Roman Empire legionaries and gladiators before widespread adoption of the spatha.

The gladius is straight and double-edged, with a V-shaped tip, and primarily constructed for thrusting action and use together with a large rectangular shield, the scutum. The cross-section of the gladius is typically rhomboid, providing the blade with good stability for stabbing.

The gladius is frequently depicted in coats of arms, especially of military corps.

The name is latin, and the diminutive form is gladiolus, also the name of a flowering plant with sword-shaped leaves.