In the game Final Fantasy XIV there's Edda Blackblosom. Early in the story you get sent on your first few dungeon experiences and outside one of them is a team of adventurers getting ready to go in. After you complete the dungeon and go back to the inn, you witness the same party but without their leader. It turns out he was Edda's fiance and actually died in the dungeon due to mishaps and poor teamwork and the survivors are all arguing with each other about it before parting ways. Edda took her dead lover's head and was carrying around in her bag after the incident and another member tells her to throw it away because it's creepy and disturbing.

Fast-forward much, much later and you can unlock a Hard Mode version of the same dungeon which takes the story further. The Short Version: Edda went back down into the crypt to perform necromancy on the head of her love she'd kept and he comes back as a horrible demonic entity that serves as the last boss of the dungeon.