a person is burned alive
Something missing from this list?
Mater Tenebrarum, the Mother of Darkness, is trapped in a burning building in the end and most likely dies. She is however a witch and we don't know if she can die that easily.
It's a major plot point that a little girl is burned alive by a cult as part of a ritual. A later scene also shows the same cult burning a police officer to death in graphic detail. It's implied that the cult uses this method of execution often.