This category lists characters who have died. The contents are obviously a significant spoiler.
For mortals from Medius, death is not necessarily permanent as their souls travel to the Afterlife. From there, they may be reincarnated, or possibly even escape and be revived. Other beings, like Angels and Demons, will die permanently though, their presence in this category indicates that they have been removed from the plot entirely (except for fake-outs, flashbacks and so forth).