OPHION

a Titan, was married to Eurynome, with whom he shared the supremacy previous to the reign of Cronos and Rhea; but being conquered by the latter, he and Eurynome were thrown into Oceanus or Tartarus. (Apollonius Rhodius. i. 503)

There are two other mythical beings of the same name. ( Metamorphoses by Ovid xii.)

From The Argonautica by Apollonius Rhodius

(ll. 496-511) He sang how the earth, the heaven and the sea, once mingled together in one form, after deadly strife were separated each from other; and how the stars and the moon and the paths of the sun ever keep their fixed place in the sky; and how the mountains rose, and how the resounding rivers with their nymphs came into being and all creeping things. And he sang how first of all Ophion and Eurynome, daughter of Ocean, held the sway of snowy Olympus, and how through strength of arm one yielded his prerogative to Cronos and the other to Rhea, and how they fell into the waves of Ocean; but the other two meanwhile ruled over the blessed Titan-gods, while Zeus, still a child and with the thoughts of a child, dwelt in the Dictaean cave; and the earthborn Cyclopes had not yet armed him with the bolt, with thunder and lightning; for these things give renown to Zeus.