Euroswydd is a figure in Welsh mythology

Welsh mythology

Welsh mythology, the remnants of the mythology of the pre-Christian Britons, has come down to us in much altered form in medieval Welsh manuscripts such as the Red Book of Hergest, the White Book of Rhydderch, the Book of Aneirin and the Book of Taliesin....

, the father of Nisien

Nisien

Nisien is a figure in Welsh mythology, the son of Penarddun and Euroswydd and twin brother of Efnisien. He appears in the Second Branch of the Mabinogi, which names Bran the Blessed, Branwen, and Manawydan as his half-siblings. Nisien, also Nissyen, was the opposite of his brother Efnisien in...

 and Efnysien by Penarddun

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, a conniving troublemaker...

, daughter of Beli Mawr

Beli Mawr

Beli Mawr was an ancestor figure in medieval Welsh literature and genealogies. He is the father of Caswallawn, Arianrhod, Lludd Llaw Eraint, Llefelys, and Afallach. In certain medieval genealogies he is listed as the husband of Anna, cousin of the Virgin Mary...

. In the Second Branch of the Mabinogi

Mabinogion

The Mabinogion is the title given to a collection of eleven prose stories collated from medieval Welsh manuscripts. The tales draw on pre-Christian Celtic mythology, international folktale motifs, and early medieval historical traditions...

Penarddun is the wife of Llŷr

Llyr

Llŷr is a figure in Welsh mythology, the father of Brân, Brânwen and Manawydan by Penarddun. The Welsh Triads mention he was imprisoned by Euroswydd; the Second Branch of the Mabinogi names Euroswydd as the father of Penarddun's younger two sons, Nisien and Efnisien. Llŷr corresponds to Lir in...

, by whom her children are Brân

Bran the Blessed

Brân the Blessed 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 the Mabinogi, Branwen ferch Llŷr. He is a son of Llŷr and Penarddun, and the brother of Brânwen, Manawydan, Nisien and Efnysien...

, Branwen

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...

, and Manawydan

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 originated from the same Celtic deity as Manannán...

. The circumstances of Nisien and Efnysien's conception are not described, but one of the Welsh Triads

Welsh Triads

The Welsh Triads are a group of related texts in medieval manuscripts which preserve fragments of Welsh folklore, mythology and traditional history in groups of three. The triad is a rhetorical form whereby objects are grouped together in threes, with a heading indicating the point of likeness...

mentions that Euroswydd had held Llŷr captive as one of the Three Exalted Prisoners of the Island of Britain; it is likely the traditions are connected.