Daeron was the minstrel of Doriath.
Daeron loved Lúthien, daughter of Thingol and Melian the Maia, but she did not love him. Nevertheless they were good friends, and Lúthien would often dance to his music. After Daeron found out about Lúthien's love for the mortal Beren, he betrayed them both to Thingol. When Lúthien later sought his help in assisting captive Beren, Daeron again betrayed her to Thingol.
After Lúthien departed in secret from Doriath Daeron repented, and set out to search for her. He never did find her and never returned to Doriath either, passing over the Ered Luin into Eriador where he dwelt apparently long after.
Daeron is mentioned as one of the greatest minstrels of all the Children of Ilúvatar, and only Maglor son of Fëanor is said to come close to his skill. Also in the Lay of Leithian there is named one called Tinfang Gelion who is counted among the three great minstrels, along with Maglor and Daeron (there spelt Dairon}.
In earlier versions of the mythology as set out in The History of Middle-earth, Daeron was originally envisioned as Lúthien's brother.