Death Gods or Grim Reapers (Shinigami in Japanese) are the personification of Death itself who rule over the souls of the departed, or its harbingers at the very least. They are often portrayed as malevolent or neutral due to humanity's natural fear of the afterlife or perceived lack of it by some.
Death Gods in fiction tend to be greedy Collectors of Souls who plot against life or ally with evil figures, yet they are also often portrayed as a Necessary Evil since they are often needed to maintain the cycle of life and death.
Examples of Death Gods:
Death is the Grim Reaper of Christianity, Judism, Islam, etc.