Author Lloyd Alexander picked the best of Celtic mythological characters, Gwydion, for his Chronicles of Prydain series. In doing so, he created the uber-cool Prince Gwydion, mentor to young Taran.

A heavy metal band named Gwydion likes to rock out—it took its name from the magical Welsh hero.

The Milky Way was sometimes called "Caer Gwydion" in Welsh mythology. Not because of his love for candy, though. Gwydion allegedly created the Milky Way by cruising through the universe to find Blodeuwedd and leaving a track behind him. (Source.)

Gwydion's got a thing for forestry. His name may come from the Old Welsh name meaning "born of trees." (Source.)