Underground Cell Key is a Key Item in Bloodborne. It was added with The Old Hunters DLC
| "Key to the cell below the Grand Cathedral.
Hunters are held within the underground cell, so that things better left unseen, better left unknown, will decay quietly in the fallow darkness"
- Used to unlock the cells after the Underground Corpse Pile to obtain the Church Pick from a Yahar'gul hunter and Yamamura Hunter Set from Old Hunter Yamamura.
- Research Hall: in Patient Room Floor 3, accessed after rotating the staircase. Key is on a dead body there. (Beware of attack from behind!)
- Player note 1