One always sees the image of Kīrtimukha on the śukanāsa of any traditionally constructed temple. This peculiar figure consists in itself the symbolism of simha, kāla and rāhu. Simha, which is the vāhana of kriyā-śakti Nārāyaṇī, represents victory over enemies. Scriptures frequently refer to both Paramēśvara and Nārāyaṇa as simha. The story of Srīmannārāyaṇa severing the head of Rāhu is well-known. In the image of Kīrtimukha, one sees the death-giving wrath of the Divine as also the power to breathe life into death – the two pieces signified by Rāhu and Nr̥simha respectively.
There are various legends surrounding the appearance of Kīrtimukha. According to Padma purāṇa (uttarakhaṇḍa, X) and Skanda purāṇa (viṣṇukhaṇḍa, kārtikamāsa māhatmya), Rāhu accepted the role of the dūta of the asura Jālandhara and approached Mahādēva with the demand to handover Pārvatī to his master. The tremendous anger of Mahārudra outpoured from his third eye in the form of a ferocious being of utmost power; with a lion face and lolling tongue, shooting lightning rods from eyes. Rāhu at once fell at the feet of the great Lord and sought refuge. The ever compassionate Lord offered refuge to Rāhu and commanded the fiery being to consume itself. The fiery creation of Mahākāla consumed its own body and was left only with its head remaining. This head came to be known as the Kīrtimukha.
Rāhu represents the act of grāsa or devouring of the sun and the moon whereas in this case, the great Nr̥simhātmaka śaiva tejas of Paramātman devoured the devourer. Rāhu also represents tamas or darkness as he overpowers the brilliance of even the sun with his own darkness, earning him the name svarbhānu. If seen carefully, Rāhu himself is an aspect of kāla who regulates the courses of sun and moon by devouring them and later releasing the two. Rāhu himself is devoured by simha, here representing Mahākāla, who exhibits supreme mastery over time and beyond. Both nigraha and anugraha aspects of the Lord are reminded to us in the form of Kīrtimukha as also the aspects of tamas and its transcendence.
According to legends from the śaivāgamas, shiva assumed the form of Sharabha to control the wrath of Nr̥simha who had begun to terrorize the worlds after slaying Hiraṇyakaśipu. Sharabha seized the form of Nr̥simha and out of his chopped head arose the form of Kīrtimukha. It must be noted that Hiranyakaśipu is the brother of Simhikā, of who was born Rāhu. As a mark of respect to Nr̥simha, the devotee is instructed to worship Kīrtimukha before worshiping the main deity within the sanctum. From the skin of Nr̥simha, the same āgama recounts were made an āsana which came to be known as simhāsana.
Vāstu and Rāhu are described as sons of Kaśyapa, one resting at the base of the dēvatā-gr̥ha and the other fixed above the śikhara. The other related variants include Garuḍamukha, Kālamakara, śaṅkhamukha, Kālamukha etc.
In Buddhist Tantra, Kīrtimukha is associated with Aruṇa, the elder brother of Garuḍa. Bodhisattva Manjushri is described to have placed the figure of Aruṇa atop Buddhist shrines showing his fiery face devouring serpents – to safeguard worshipers from wrathful beings, chiefly from the nāgas. A Buddhist’s fear of the nāgas is evident even from the Pali Suttas.
Kīrtimukha also finds a place in the jaṭāmaṇḍala of Tatpuruṣa mūrti and is worshiped during the five-fold āvaraṇa-krama of śuddha-prāsāda mantra.