In the military of classical antiquity, a clipeus (Ancient Greek: ) was a large shield worn by the Greek hoplites and Romans as a piece of defensive armor, which they carried upon the arm, to protect them from the blows of their enemies. It was round in shape and in the middle was a bolt of iron, or of some other metal, with a sharp point. The clipeus was more-or-less identical to the earlier aspis.
Pliny the Elder also describes the custom of having a bust-portrait of an ancestor painted on a clipeus, and having it hung in a temple or other public place. From this round bas-reliefs in a medallion on sarcophagi and in other forms are known as "clipeus portraits".
The clipeus was used by Romans during the Roman Kingdom and early republic but was replaced by the legionary scutum, a convex rectangular shield, in the later Roman Republic. However, the scutum disappeared during the Crisis of the Third Century. All troops adopted the auxiliary oval (and sometimes round or hexagonal) shield (parma or clipeus). Shields, from examples found at Dura-Europos and Nydam Mose, were of vertical plank construction, the planks glued, and faced inside and out with painted leather. The edges of the shield were bound with stitched rawhide, which shrank as it dried, improving structural cohesion. It was also lighter than the edging of copper alloy used in earlier Roman shields.