Nisien is a figure in

Welsh mythology Welsh mythology (Welsh: ''Mytholeg Cymru'') consists of both folk traditions developed in Wales, and traditions developed by the Celtic Britons elsewhere before the end of the first millennium. As in most of the predominantly oral societies Celti ...

, the son of

Penarddun Penarddun is a figure in Welsh mythology, the wife of Llŷr. The Second Branch of the ''Mabinogi'' names Bran, Branwen, and Manawydan as her children by Llŷr, and ascribes to her two additional sons by Euroswydd: Nisien, a good man, and Efnysien ...

and

Euroswydd Euroswydd is a figure in Welsh mythology, the father of Nisien and Efnysien by Penarddun, daughter of Beli Mawr. In the Second Branch of the ''Mabinogi'' Penarddun is the wife of Llŷr, by whom her children are Brân, Branwen, and Manawydan. The ...

and twin brother of

Efnysien Efnisien fab Euroswydd (also spelled Efnissien or Efnysien) is a sadistic anti-hero in Welsh mythology, appearing prominently in the tale of ''Branwen ferch Llŷr'', the second branch of the Mabinogi. Described by Will Parker as "a study in the psy ...

. He appears in the Second Branch of the Mabinogi, which names

Brân the Blessed Brân the Blessed ( cy, Bendigeidfran or ''Brân Fendigaidd'', literally "Blessed Crow") is a giant and king of Britain in Welsh mythology. He appears in several of the Welsh Triads, but his most significant role is in the Second Branch of ...

Branwen Branwen, Daughter of Llŷr is a major character in the Second Branch of the ''Mabinogi'', which is sometimes called the "Mabinogi of Branwen" after her. Branwen is a daughter of Llŷr and Penarddun. She is married to Matholwch, King of Ireland, ...

, and

Manawydan Manawydan fab Llŷr is a figure of Welsh mythology, the son of Llŷr and the brother of Brân the Blessed and Brânwen. The first element in his name is cognate with the stem of the name of the Irish sea god Manannán mac Lir, and likely origina ...

as his half-siblings. Nisien, also Nissyen, was the opposite of his brother Efnisien in personality. He was tranquil and generous, while Efnisien was vindictive and destructive.

References

Welsh mythology {{Celt-myth-stub