The term Demiurge derives from the Latinized form of the Greek term dēmiourgos, δημιουργός (literally "public or skilled worker"), and refers to an entity responsible for the creation of the physical universe and the physical aspect of humanity. The term dēmiourgos occurs in a number of other religious and philosophical systems, most notably Platonism. Moral judgements of the demiurge vary from group to group within the broad category of Gnosticism — such judgements usually correspond to each group's judgement of the status of materiality as being inherently evil, or else merely flawed and as good as its passive constituent matter will allow. In Gnosticism the Demiurge, creator of the material world, was not God but the Archon.

As Plato does, Gnosticism presents a distinction between a supranatural, unknowable reality and the sensible materiality of which the demiurge is creator. However, in contrast to Plato, several systems of Gnostic thought present the Demiurge as antagonistic to the Supreme God: his act of creation either in unconscious and fundamentally flawed imitation of the divine model, or else formed with the malevolent intention of entrapping aspects of the divine in materiality. Thus, in such systems, the Demiurge acts as a solution to the problem of evil. In the Apocryphon of John (several versions of which are found in the Nag Hammadi library), the Demiurge has the name "Yaltabaoth", and proclaims himself as God:

"Now the archon who is weak has three names. The first name is Yaltabaoth, the second is Saklas, and the third is Samael. And he is impious in his arrogance which is in him. For he said, 'I am God and there is no other God beside me,' for he is ignorant of his strength, the place from which he had come."

"Samael", in the Judeo-Christian tradition, refers to the evil angel of death, and corresponds to the Christian demon of that name, one second only to Satan. Literally, it can mean "blind god" or "god of the blind" in Aramaic (Syriac sæmʻa-ʼel); another alternative title is "Saklas", Aramaic for "fool" (Syriac sækla "the foolish one").

Gnostic myth recounts that Sophia (Greek, literally meaning "wisdom"), the Demiurge's mother and a partial aspect of the divine Pleroma or "Fullness", desired to create something apart from the divine totality, and without the receipt of divine assent. In this abortive act of separate creation, she gave birth to the monstrous Demiurge and, being ashamed of her deed, she wrapped him in a cloud and created a throne for him within it. The Demiurge, isolated, did not behold his mother, nor anyone else, and thus concluded that only he himself existed, being ignorant of the superior levels of reality that were his birthplace.

The Gnostic myths describing these events are full of intricate nuances portraying the declination of aspects of the divine into human form; this process occurs through the agency of the Demiurge who, having stolen a portion of power from his mother, sets about a work of creation in unconscious imitation of the superior Pleromatic realm. Thus Sophia's power becomes enclosed within the material forms of humanity, themselves entrapped within the material universe: the goal of Gnostic movements was typically the awakening of this spark, which permitted a return by the subject to the superior, non-material realities which were its primal source.