Who actually sings the Hex Girls songs in Scooby Doo episodes?

The Hex Girls' songs in Scooby-Doo episodes are actually sung by the voice actresses who play them:

* Luna: Grey DeLisle (also known as Grey Griffin)

* Terra: Jennifer Hale

* Willa: Tara Strong

Interestingly, all three actresses are quite well-known voice actors in their own right, with long and varied careers in animation and video games!