Pañcānana (पंचानन) Śiva or the five-faced one represents the five aspects of Siva.The Vidyeśvarasaṃhitā of the Śiva purāṇa makes a reference to the five aspects or vyūhas of Śiva.
“I meditate on Śiva, the lord of Ambikā (Pārvatī), auspicious from the beginning to the end, having no parallel, the noble lord, the unaging and undying, the lord of Ātmans, five-faced and the dispeller of the five powerful sins.”
In the Śatarudrasaṃhitā of the Śiva purāṇa, the five forms of Maheśa are listed as Īśāna, Puruṣa or Tatpuruṣa, Aghora, Vāma and Brahman, symbolic of the scheme of creation evolved out of 25 constituents: five gross and five subtle elements, five organs of action and five of knowledge, besides the mind, ego, the intellect, nature and the ātman.
Excerpt from the Śiva purāṇa wherein Nandīśvara explains the incarnations of Śiva:
“The five famous forms of Maheśa are Īśāna, Puruṣa, Aghora, Vāma and Brahman. Īśāna form of Śiva is the first and the principal one. It directly occupies and presides over the individual soul, the enjoyer of prakṛti. The tatpuruṣa form of Śiva is the second. It occupies and presides over every object of enjoyment, the support of the attributes. The third is Aghora that stands within, occupies and presides over the principle of intelligence with all its ramifications for the sake of Dharma. The fourth form of Śiva is Vāmadeva who presides over the ego and is engaged in many incessant activities. These forms of Śiva, the fountainhead of all glory shall be honoured and worshipped assiduously by those who seek glory.”
The great mūrti of Śiva in the Elephanta caves represents the Pañca-Brahma form, also known as Maheśamūrti in which the frontal view depicts three heads only, the fourth one is at the back, concealed from view and the fifth one, present above, is not depicted, since it is representative of the invisible ākāśa or avyakta prakṛti aspect.
In the painting above, Pañchanāna Śiva seated regally with Pārvati — holding his attributes on a lotus bed within an elaborate gold dais under a golden jeweled domed pavilion. Maharaja Ranbir Singh (1830–85) stands respectfully in devotion to the Lord, also attended by Kārtikēya and Gaṇeśa. Below them dancers, celestial horse-headed musicians, Śiva, Ṛṣis and Dēvas celebrate. Maharaja Ranbir Singh succeeded his father Gulab Singh as ruler of Jammu and Kashmir in 1857 and reigned until his death in 1885. His profile was quite distinctive with his upwardly pointing mustachio and Dogra-style rounded turban. He is pictured here with his palms pressed together respectfully, in the presence of Śiva and Pārvati.
References: Siva Purana by J. L. Shastri