The Werewolf of Allariz

Spain's first serial killer was a man who claimed to be a werewolf. Manuel Romasanta reported being under a witches curse for years causing him to become a werewolf and prey on those in the woods. But as a human, he was a guide for vulnerable women and children, seeking out a better life. After murdering them, he would send letters to family in an attempt to show they were doing well. Meanwhile he would sell their belongings and reportedly use their body fat to create soaps. Manuel was sentenced to death, then changed to life in prison at the decree of Queen Isabell II, dying in prison before he turned 60.

Sources:

https://www.fascinatingspain.com/articulo/history-and-legends/the-werewolf-of-allariz-first-spanish-serial-killer/20221026090934068670.html

https://phmuseum.com/galleries/lobismuller

https://galiciaalive.com/en_US/tag/manuel-blanco-romasanta/

https://thehorrorcollection.com/manuel-blanco-romasanta-werewolf/