Manannan Mac Lir

Manannan Mac Lir is the chaotic god of the Knight pantheon.

Encyclopedia entry

Normally called Manannan, Ler's son was the patron of
merchants and sailors.  Manannan had a sword which never
failed to slay, a boat which propelled itself wherever its
owner wished, a horse which was swifter than the wind, and
magic armour which no sword could pierce.  He later became
god of the sea, beneath which he lived in Tir na nOc, the
underworld.