Blodeuwedd (Welsh pronunciation: [blɔˈdeiwɛð]; Welsh for "Flower-Faced," a name made up of "blodau" meaning "flowers" and "gwedd" meaning "face") is married to Lleu Llaw Gyffes in Welsh mythology. She was created from the flowers of broom, meadowsweet, and oak by the magical beings Math and Gwydion. Blodeuwedd plays an important role in the story Math fab Mathonwy, which is the last part of the Four Branches of the Mabinogi.

Role in Welsh tradition

The hero Lleu Llaw Gyffes was cursed by his mother, Arianrhod, to never have a human wife. To stop this curse, the magicians Math and Gwydion took flowers from the oak, broom, and meadowsweet. They used magic to create a beautiful maiden and named her Blodeuwedd. They performed a ritual, as was done at that time, to give her life.

Later, while Lleu was away, Blodeuwedd had an affair with Gronw Pebr, the lord of Penllyn. Together, they planned to kill Lleu. Blodeuwedd tricked Lleu into revealing how he could be killed. He explained that he could not be harmed during the day or night, indoors or outdoors, while riding or walking, clothed or naked, or by any weapon made by law. He said he could only be killed at dusk, wrapped in a net, with one foot on a bath and one on a black goat, by a riverbank, and with a spear forged for a year during the time when people were at Mass. Blodeuwedd used this information to arrange his death.

When Lleu was struck by the spear thrown by Gronw, he turned into an eagle and flew away. Gwydion found him perched on an oak tree. Gwydion sang a special song called englynion Gwydion to lure Lleu down and change him back to human form. Gwydion and Math cared for Lleu until he recovered. They then gathered the forces of Gwynedd and reclaimed Lleu’s lands from Gronw and Blodeuwedd.

Gwydion caught Blodeuwedd and turned her into an owl, a bird hated by all others. He declared that she would never be seen in daylight again, as other birds would harass and despise her wherever she went. Her name, Blodeuwedd, means "flower-face" in modern Welsh. This is why owls are still called Blodeuwedd today, and why birds and owls are enemies.

Meanwhile, Gronw fled to Penllyn and sent messengers to Lleu, asking for forgiveness. Lleu refused and demanded that Gronw stand by the River Cynfael and take a blow from Lleu’s spear. Gronw begged his men to take the blow instead, but they refused. Eventually, Gronw agreed to accept the blow, asking to place a large stone between himself and Lleu. Lleu allowed this and threw the spear with such force that it pierced the stone, killing Gronw. A stone with a hole in it near Ardudwy is still called Llech Ronw (Gronw’s Stone).

Robert Graves and others believe lines 142–153 of Cad Goddeu are a "Song of Blodeuwedd."