In
Irish mythology,
Nechtan was the father and/or husband of
Boann. He may be
Nuada under another name, or his cult may have been replaced by that of Nuada. Only he and his three cup-bearers were permitted to visit the
well of Segais, into which nine sacred
hazel trees dropped their wisdom-bearing nuts. When Boann visited the well, it overflowed and chased her to the coast, forming the river
Boyne.
The name 'Nechtan' is perhaps cognate with that of the Romano-British god, Nodens, or the Roman god, Neptune, and the Persian and Vedic gods sharing the name Apam Napat. It may also be cognate to the Swedish mythological being Näcken, who dwells near wells and springs.
Nechtan or Nectan became a common Celtic name and a number of historical or legendary figures bear it.