His role varies within the Vedic texts such as being one who created heaven and earth, all of water and beings, the chief, the father of gods, the creator of devas and asuras, the cosmic egg and the Purusha (spirit). His role peaked in the Brahmanas layer of Vedic text, then declined to being a group of helpers in the creation process. In some Brahmana texts, his role remains ambiguous since he co-creates with the powers with goddess Vāc (sound).
In the Rigveda, Prajapati appears as an epithet for Savitr, Soma, Agni and Indra, who are all praised as equal, same and lord of creatures. Elsewhere, in hymn 10.121 of the Rigveda, is described Hiranyagarbha (golden embryo) that was born from the waters containing everything, which produced Prajapati. It then created manah (mind), kama (desire) and tapas (heat). However, this Prajapati is a metaphor, one of many Hindu cosmology theories, and there is no supreme deity in the Rigveda. One of the striking features about the Hindu Prajapati myths, states Jan Gonda, is the idea that work of creation is a gradual process, completed in stages of trial and improvement.
In the Shatapatha Brahmana, embedded inside the Yajurveda, Prajapati emanated from Purusha (cosmic spirit) and Prajapati co-creates the world with the goddess of Language. It also includes the "golden cosmic egg" mythology, wherein Prajapati is stated to be born from a golden egg in primeval sea after the egg was incubated for a year. His sounds became the sky, the earth and the seasons. When he inhaled, he created the devas (gods), fire and light. When he exhaled, he created the asuras (demons) and darkness. Then, together with the goddess of Language, he created all beings and time. In Chapter 10 of the Shatapatha Brahmana, as well as chapter 13 of Pancavimsa Brahmana, is presented another theory wherein he (Prajapati) is a mother, becomes self-pregnant with all living creatures self-generated, then evil Mrtyu seizes these beings within his womb, but because these beings are part of the eternal Prajapati, they desire to live long like him.
The Aitareya Brahmana offers a different myth, wherein Prajapati, having created the gods, metamorphosed into a stag and approached his daughter Dawn who was in the form of a doe, to produce other earthly beings. The gods were horrified by the incest, and joined forces to produce angry destructive Rudra to punish Prajapati for "doing what is not done". Prajapati was killed by Rudra. The Kausitaki Brahmana offers yet another myth, wherein Prajapati created from his own self fire, sun, moon, wind and feminine dawn. The first four saw dawn and released their seeds, which became existence (Bhava).
In section 2.266 of Jaiminiya Brahmana, Prajapati is presented as a spiritual teacher. His student Varuna lives with him for 100 years, studying the art and duties of being the "father-like king of gods".
Prajapati appears in early Upanishads, among the most influential texts in Hinduism. He is described in the Upanishads in diverse ways. For example, in different Upanishads, he is presented as the personification of creative power after Brahman, the same as the wandering eternal soul, as symbolism for unmanifest obscure first born, as manifest procreative sexual powers, the knower particularly of Atman (soul, self), and a spiritual teacher that is within each person. The Chandogya Upanishad, as an illustration, presents him as follows:
The self (atman) that is free from evils,
free from old age and death,
free from sorrow, free from hunger and thirst;
the self whose desires and intentions are real –
that is the self that you should try to discover,
that is the self that you should seek to perceive.
When someone discovers that self and perceives it,
he obtains all the worlds, and all his desires are fulfilled,
In the Mahabharata, Brahma is declared to be a Prajapati who creates many males and females, and imbues them with desire and anger, the former to drive them into reproducing themselves and the latter to prevent them from being like gods. Other chapters of the epics and Puranas declare Shiva or Vishnu to be Prajapati.
The Grhyasutras include Prajapati as among the deities invoked during wedding ceremonies and prayed to for blessings of prosperous progeny, and harmony between husband and wife.
Prajapati is identified with the personifications of Time, Fire, the Sun, etc. He is also identified with various mythical progenitors, especially (Manu Smrti 1.34) the ten lords of created beings first created by Brahmā: the Prajapatis Marichi, Atri, Angiras, Pulastya, Pulaha, Kratu, Vasishtha, Prachetas or Daksha, Bhrigu and Nārada.
In the Puranas, there are groups of Prajapati called Prajapatayah who were rishis (sages) or "grandfathers" from whom all of humanity resulted, followed by a Prajapatis list that widely varies in number and name between different texts. According to George Williams, the inconsistent, varying and evolving Prajapati concept in Hindu mythology reflects the diverse Hindu cosmology.
The Mahabharata and the genre of Puranas call various gods and sages as Prajapati. Some illustrations, states Roshen Dalal, include Agni, Bharata, Shashabindu, Shukra, Havirdhaman, Indra, Kapila, Kshupa, Prithu-Vainya, Soma, Svishtakrit, Tvashtr, Vishvakarma and Virana.