Kashyapa (Sanskrit कश्यप kaśyapa) was an ancient sage (rishis), who is one of the Saptarshis in the present Manvantara; with others being Atri, Vashishtha, Vishvamitra, Gautama, Jamadagni, Bharadwaja 
He was the father of the Devas, Asuras, Nagas and all of humanity. He married Aditi, with whom he fathered Agni, the Aditya. With his second wife, Diti, he begot the Daityas. Diti and Aditi were daughters of King Daksha Prajapati and sisters to Sati, Shiva's consort.
Diti conceived a child in the evening time, whom she carried for a hundred years in the womb. She thus gave birth to Hiranyaksha.
In the very beginning of time and creation, the Hindu god Vishnu used to live by the shores of a great vast sea. A pair of seagulls also nested on the same shore. Every year the female seagull would lay her eggs by the shore of the sea. But the sea would sweep in and wash her eggs away. The female seagull laid her eggs farther ashore every year but the sea would continue to sweep in and wash them away every single time. The seagulls were heartbroken by their loss. In despair, they appealed to Vishnu, the great Preserver, to come to their aid. Vishnu felt pity and compassion for their hapless situation. He opened his mouth and swallowed the sea in a huge gulp. Where the sea was, now lay the newly created Mother Earth. Vishnu was very exhausted by the feat of swallowing up such a vast sea. He lay down to rest and soon fell into a deep sleep. The demon Hiranyaksha was lurking nearby. When he saw Vishnu asleep, he seized the opportunity and brutally assaulted the defenseless Mother Earth. His brutality was of such great magnitude that her limbs were broken and levered up. These broken limbs, towering towards the sky, formed the mighty Himalayas.
He was slain by the god Vishnu after he (Hiranyaksha) took the Earth to the bottom of what has been described as the "Cosmic ocean".
He had an elder brother named Hiranyakashipu, who after having undertaken penances which made him incredibly powerful and invincible unless several conditions were met, was later slain by Narasimha, another avatar of Vishnu.
- Dictionary of Hindu Lore and Legend (ISBN 0-500-51088-1) by Anna Dhallapiccola