In Celtic mythology, Elphin (in Welsh, "Elfyn") was a son of Lord Gwyddno Garanhir of Gwynedd.

Elphin was extremely unlucky. Gwyddno sent Elphin to a spot known for salmon and had him fish. Instead, Elphin found a baby and called it Taliesin ("radiant brow"). Along the way back to his father, Taliesin, though still a baby, spoke in beautiful poetry.

A few years later, King Maelgwn who demanded that Elphin praise him and his court. Elphin refused, claiming Taliesin was a better bard and his wife a prettier woman than anyone the King had in his court. Taliesin knew what was happening, because he was a seer, and told Elphin's wife. Maelgwn's son Rhun went to Elphin's house to seduce his wife and prove Elphin's claims weren't true. Rhun got her drunk. When she passed out, Rhun tried to take her wedding ring off to prove her unfaithfulness; since the ring wouldn't come off, he cut off her finger. When King Maelgwn attempted to show the finger to Elphin, he pointed out that his wife cut her fingernails more often than the owner of the finger, had servants to kneed dough and never had any under her nails, and her ring was loose on her finger, and that one was tight.

Maelgwn demanded Taliesin come to his court to prove the other claim wrong. Taliesin gave twenty minutes for both himself and the King's bards to come up with an epic. The royal bards couldn't do it. When it came Taliesin's time, he caused a massive wind to rattle the castle. Frightened, Maelgwn sent for Elphin. Taliesin's next song caused Elphin's chains to detach. Maelgwn challenged the pair to a horse race. Taleisin arrived the next day with an old, weak horse. As each of the king's horses passed him at the very start of the race, Taliesin touched its rump with a twig of holly. When they had all passed, he dropped his hat to the ground. When the king's horses came back, right before the finish line, they stopped at the holly twigs Taliesin had laid there, and began to dance. Taliesin's old horse strolled back in quite a bit later and won the race.