Amūrtarayas (Amurtarayas) or Amūrtarayā (Amurtaraya) was the father of Gaya, the greatest among Rājarṣi(s) (Rajarshi; a king with the attributes of a seer) — amūrtarayasaḥ putro gayo rājarṣisattamaḥ. In Mahābhārata (Mahabharata), a learned Brāhmaṇa (Brahmana) called Śamaṭha (Samatha) told the legend of Gaya to Pāṇḍava(s) (Samatha), during their exile in forest.
In ancient times, the sword used by God Rudra, for slaying demons, came to Manu, through several other deities like Viṣṇu (Vishnu)and Indra. In the lineage of Manu, that sword finally came to Amūrtarayā, through the hand of Puru, son of Yayāti (Yayati). From him, king Bhūmiśaya (Bhumisaya) received it. Since there was no other famous king called Amūrtarayā in Mahābhārata, this Amūrtarayā seems to be the same father of Gaya.