Valper Galilei

Valper Galilei is a minor antagonist in High School DxD. He is an elderly former priest and the lead researcher behind the Holy Sword Project, a secret Church experiment that involved kidnapping and performing cruel human experiments on children (including Yuuto Kiba) to artificially create wielders capable of using holy swords like the fragments of Excalibur. Those who failed were discarded or killed.

Driven by an obsessive fascination with holy swords (especially Excalibur) since childhood, he became bitter after discovering he himself could not wield them. After being excommunicated from the Church, he allied with the Fallen Angel Kokabiel during the events of Volume 3/Season 2, seeking revenge and chaos. He is eventually betrayed and killed by Kokabiel.

He appears as a short, bespectacled old man with gray hair, a mustache, and priest robes, and is portrayed as a ruthless, fanatical scientist willing to sacrifice innocents for his research goals.