Atithi was a king of the Ikṣvāku (Ikshvaku) dynasty, son of Kuśa (Kusha) and grandson of Rāmacandra (Ramachandra). Atithi had a son called Niṣadha (Nishadha). 

Bhāgavatpurāṇa Vols. 1-12(9.12.1)
Brahmāṇḍapurāṇa (Maharṣi)(2.63.201)
Matsyapurāṇa(12.52)
Vāyupurāṇa(88.201)
Viṣṇupurāṇa(4.4.48)