I have murdered you to satisfy my insatiable lust, my beastly appetite!
After basing his character in Horror Rises from the Tomb on the infamous Barón Gilles de Lancré, Paul Naschy went back to the source and told the Barón's own story in 1974's Devil's Possessed (a.k.a. The Marshall from Hell). Instead of just the prologue being set in the past, this time the entire film takes place in medieval times, which allows Naschy to play up his character's Macbeth-like relationship with his domineering wife (Norma Sebre) and toss in a Robin Hood-like band of outlaws for good measure. Naschy also makes sure we know how conflicted he is about the hardships he inflicts on his subjects in his quest for the philosopher's stone, which his personal alchemist (Eduardo Calvo) assures him can only be obtained by sacrificing young maidens for their blood and taking part in Satanic rituals. No wonder he's so unpopular.
Eventually the oppressed people gain a champion in returning soldier Guillermo Bredeston, who fought alongside Naschy in the Hundred Years' War and languished in an English prison for four years, which is how he missed the part where his best friend became a murderous villain. After joining up with the outlaws (and showing off his superior fighting skills on more than one occasion), Bredeston faces Naschy in a joust in which the latter loses an eye, which only serves to make the nobleman look more monstrous. He's also plagued by nightmares and aural hallucinations, which eventually inspire him to enter a monastery. That, however, proves short-lived for soon enough he's out for revenge against Bredeston and his main squeeze (Graciela Nilson, whose feathered blond hair doesn't exactly evoke the period very well), and the film ends with a vigorous duel to the death which director León Klimovsky actually stages pretty well. Sure, he cops it to some extent from Kurosawa's Throne of Blood, but if you're going to steal, you might as well steal from the best.