An acroterion, acroterium, is an architectural ornament placed on a flat pedestal called the acroter or plinth, and mounted at the apex or corner of the pediment of a building in the classical style. An acroterion placed at the outer angles of the pediment is an acroterion angularium.

Pediments are a form of gable in classical architecture, usually of a triangular shape. Pediments are placed above the horizontal structure of the cornice, or entablature if supported by columns. In ancient architecture, a wide and low triangular pediment typically formed the top element of the portico of a Greek temple, a style continued in Roman temples. But large pediments were rare on other types of building before Renaissance architecture. For symmetric designs, it provides a center point and is often used to add grandness to entrances.