In the practice of religion, a cult image is a human-made object that is venerated or worshipped for the deity, spirit or daemon that it embodies or represents. In several traditions, including the ancient religions of Egypt, Greece and Rome, and Hinduism, cult images in a temple may undergo a daily routine of being washed, dressed, and having food left for them. Processions outside the temple on special feast days are often a feature. Religious images cover a wider range of all types of images made with a religious purpose, subject, or connection. In many contexts "cult image" specifically means the most important image in a temple, kept in an inner space, as opposed to what may be many other images decorating the temple.

The term idol is an image or representation of a god used as an object of worship, while idolatry is the worship of an "idol" as though it were God.

The use of images in the Ancient Near East seems typically to have been similar to that of the ancient Egyptian religion, about which we are the best-informed. Temples housed a cult image, and there were large numbers of other images. The ancient Hebrew religion was or became an exception, rejecting cult images despite developing monotheism; the connection between this and the Atenism that Akhenaten tried to impose on Egypt has been much discussed. In the art of Amarna, Aten is represented only as the sun-disk, with rays emanating from it, sometimes ending in hands, and temples to Aten (e.g. the Great Temple of the Aten in Amarna) were open courts with no roof, that the Sun might be worshipped directly as it traveled across the sky.

Cult images were a common presence in ancient Egypt, and still are in modern-day Kemetism. The term is often confined to the relatively small images, typically in gold, that lived in the naos in the inner sanctuary of Egyptian temples dedicated to that god (except when taken on ceremonial outings, say to visit their spouse). These images usually showed the god in their sacred barque or boat; none of them survive. Only the priests were allowed access to the inner sanctuary.

There was also a huge range of smaller images, many kept in the homes of ordinary people. The very large stone images around the exteriors of temples were usually representations of the pharaoh as himself or "as" a deity, and many other images gave deities the features of the current royal family.

Ancient Greek temples and Roman temples normally contained a cult image in the cella. The cella in Greek temples was in the center, while it was located in the back of Roman temples. Access to the cella varied, but apart from the priests, at the least some of the general worshippers could access the cella some of the time, though sacrifices to the deity were normally made on altars outside in the temple precinct (temenos in Greek). Some cult images were easy to see, and were major tourist attractions. The image normally took the form of a statue of the deity, typically roughly life-size, but in some cases many times life-size, in marble or bronze, or in the specially prestigious form of a Chryselephantine statue using ivory plaques for the visible parts of the body and gold for the clothes, around a wooden framework. Most cult statues are anthropromorphic and take human shape. The most famous Greek cult images were of this type, including the Statue of Zeus at Olympia, and Phidias's Athena Parthenos in the Parthenon in Athens, both colossal statues now completely lost. Fragments of two chryselephantine statues from Delphi have been excavated.

The acrolith was another composite form, this time a cost-saving one with a wooden body. A xoanon was a primitive and symbolic wooden image, perhaps comparable to the Hindu lingam; many of these were retained and revered for their antiquity. Many of the Greek statues well-known from Roman marble copies were originally temple cult images, which in some cases, such as the Apollo Barberini, can be credibly identified. A very few actual originals survive, for example the bronze Piraeus Athena (2.35 metres high, including a helmet).

In Greek and Roman mythology, a "palladium" was an image of great antiquity on which the safety of a city was said to depend, especially the wooden one that Odysseus and Diomedes stole from the citadel of Troy and which was later taken to Rome by Aeneas. (The Roman story was related in Virgil's Aeneid and other works.)