Wikipedia
Atharvan ( ; an n-stem with nominative singular ) was a legendary Vedic sage ( rishi) of Hinduism who along with Angiras is supposed to have authored (" heard") the Atharvaveda. He is also said to have first instituted the fire-sacrifice or yagna. Sometimes he is also reckoned among the seven seers or Saptarishi. His clan is known as the Atharvanas. Atharvan married Chitti, daughter of Kardama rishi, and had a great sage Dadhichi as a son. He was referred to as a member of the Bhrigu clan.
According to mundaka upnisad and other texts, he was eldest son & ( Manasputra) born from mind of the brahma. Vedic atharvan is cognate with Avestan āθrauuan / aθaurun, "priest", but the etymology of the term is not yet conclusively established. "Attempts have been made to connect the term with Avestan atar- "fire" (not attested in Vedic); but these have been prompted by what is probably a mistaken assumption of the importance of fire in the ancient Indo-Iranian religion." (Boyce, 1982:16)