Much of the imagery used for the enemies in the game is inspired by H. P. Lovecraft.
The boss known as Amygdala gets its name from the part of the brain that is associated with the fear response. "Amygdala" is Latin for "almond" and both the creature's head and the part of the brain have an almond-like shape.
Yharnam, the main location of the game, is thought to be inspired by Windham the Demon City from the manga series "Berserk". This is likely due to Miyazaki regularly citing Berserk as a visual influence for the other Souls games.
Some of the outfits for the Hunter Attire are directly inspired by the French period movie, Brotherhood of the Wolf.
The Old Hunters DLC features five Bosses, four NPCs, three Caryll Runes, 10 Key Items, two Consumables, 11 Trick Weapons, five Firearms, three Hunter Tools, nine Armor Sets and six Trophies.