Seithenyn - in Welsh legend, he was drunk when in charge of the sea defences of Cantre'r Gwaelod and the sea overran the cantref.

Next: N

Nestor - King of Pylos

next: 'R'

Revontulet - The Finnish name for the Northern Lights. It means foxfire (or perhaps firefox) and one legend is that they are caused by the friction of the magic fox as it drags its tail across the snow.

Next: T

Lovely one Mona - thanks for the explanation.

T - Titans (Greek gods). 3 of them were also Ts -

Tethys
Theia and
Themis.

Next: U

Taking the N from Titan . . .

Na Fir Chlis. This is for Asha. It's the Scots Gaelic for the Northern Lights. It means "the nimble men," sometimes called the merry dancers - subjects of traditional tales and legends.

Next: S

S
Skinwalker - (also known as shape shifter) is a person who is able to transform themselves into any animals in some beliefs and only one particular animal in others.

next: 'R'

Rama - Hindu God (or if you're a SF fan Arthur C Clarke's big spaceship).

Next: 'A'

Aeetes - King of Colchis; keeper of Golden Fleece

next: 'S'

S
Syragh - Tulpa-like expression of the human soul, forged by rituals and meditation.

next: H