Phobos

Phobos, Greek god of Fear.
Son of Aphrodite and Ares.
First appeared in Season 1.
Was placed in Clearwater to settle an argument between his parents, kidnapping teenagers and subjecting them to terror for years at a time.
Among his captives was Jenny Swanson. She and the other captives were rescued by Fionn Corvin, Cord Van Graff and Barbie Hudson.
Fionn fought Phobos, dealing what seemed a killing blow, but Phobos stood and knocked Fionn across the cave. Barbie healed Fionn, Cord hit Phobos with an arrow that deprived him of his regeneration powers and Fionn went to fight Phobos again. This time Fionn killed Phobos, becoming The Godkiller in the process.
This has become a part of Phobos's legacy, he was the first god to die at The Godkiller's hand.