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.
In earlier versions of the mythology as set out in The History of Middle-earth, Daeron was originally envisioned as Lúthien's brother.