Sacamantecas or mantequero is the Spanish name for a kind of bogeyman or criminal characterized by killing for human fat.

Manuel Blanco Romasanta was Spain's first recorded serial killer. In 1853, he admitted to thirteen murders, but claimed he was not responsible because he was suffering from a curse that caused him to turn into a wolf. Although this defense was rejected at trial, Queen Isabella II commuted his death sentence to allow doctors to investigate the claim as an example of clinical lycanthropy. Blanco has become part of Spanish folklore as the Werewolf of Allariz and is also known as The Tallow Man, a nickname he earned for rendering his victims' fat to make high-quality soap.