Aniconism is the cultural absence of artistic representations (icons) of the natural and supernatural worlds, or it is the absence of representations of certain figures in religions. The prohibition of material representations may only extend to a specific supreme deity, or it can encompass an entire pantheon, it can also include depictions of a prophet, saints, or sages, or even depictions of living beings and anything in existence generally. It is generally codified by religious traditions and as such, it becomes a taboo. When it is enforced by the physical destruction of images, aniconism becomes iconoclasm.

Aniconism has historical phases in both Buddhism and Christianity, though these movements have been largely rejected as Buddha in art, life of Buddha in art, Buddhas and bodhisattvas in art, God the Father in Western art, Holy Spirit in Christian art, the depiction of Jesus, The Trinity in art, and Manus Dei are common. By contrast Islam has predominantly been aniconistic throughout their histories, including representations of major figures such as Muhammad. The view of aniconism in Judaism has been challenged, with a number of medieval Ashkenazi illuminated manuscripts collected by David Kaufmann. The earliest phases of ancient Greek religion were rich in aniconic representation, even though Greek mythology is heavily anthropomorphic.

The word "aniconism" is derived from Greek εικων 'image' with the negative prefix an- (Greek privative alpha) and the suffix -ism (Greek -ισμος). Iconoclasm is the active destruction of images for religious or cultural reasons.

In monotheistic religions, aniconism was shaped by theological considerations and historical contexts. It emerged as a corollary in which people believed that God was the ultimate power holder, and people who practiced it believed that they needed to defend God's unique status against competing external and internal forces, such as pagan idols and critical humans. Idolatry was seen as a threat to God's uniqueness, and one way in which prophets and missionaries chose to fight against it was through the prohibition of physical representations. The same solution worked against humans who pretended to have the same power of creation that God had (hence, their banishment from the Heavens, the destruction of Babel, and the Second Commandment in the biblical texts).

Some modern scholars who have studied various cultures have gathered material which shows that in many cases, the idea of aniconism is an intellectual construction rather than a fact of tangible reality, it suits specific intents and historical contexts.

Since the beginning of the serious study of the history of Buddhist art in the 1890s, the earliest phase, which lasted until the 1st century CE, has been described as aniconistic; the Buddha was only represented with symbols such as an empty throne, a Bodhi tree, a riderless horse with a parasol floating above an empty space (at Sanchi), Buddha's footprints, and the dharma wheel. However, other persons and their surroundings are often depicted in great numbers and care, and the scenes are often crowded, but with an empty space in the centre.

In relation to the image of the Buddha, this aniconistic tradition could have been based on an ancient Buddhist rule which prohibited images of the Buddha in which he appeared in human form, a rule which is written in the Sarvastivada vinaya (the rules of the early Buddhist school of the Sarvastivada): "Since it is not permitted to make an image of the Buddha's body, I pray that the Buddha will grant that I can make an image of the attendant Bodhisattva. Is that acceptable?" The Buddha answered: "You may make an image of the Bodhisattava".

Although they are still a subject of debate, the first anthropomorphic representations of the Buddha are frequently considered a result of the Greco-Buddhist interaction, a cultural exchange which was particularly widespread in Gandhara, a theory which was first fully expounded upon by Alfred A. Foucher, but from the start, it was criticized by Ananda Coomaraswamy. Foucher also accounted for the origins of the aniconistic symbols by collecting small souvenirs which he removed from the main pilgrimage sites and carried away, souvenirs which were later recognized and popularized as symbols of the events which occurred at the site. Other explanations stated that it was inappropriate to represent a person who had attained nirvana.