The denomination that "dark magic" indicates a form of corrupted and evil magic is actually wrong, for magic is basically neutral, not good nor bad. What is important is how the magic is used and the motives that influence a sorcerer or a witch to use such magic.
There are some applications of magic or some spells whose effects or purposes are undoubtedly evil and can only be used to inflict harm upon someone.
This page contains every spell, type of magic, creature or object which can only, without any doubt, be used for an evil purpose.
Note: human characters should not be included in this category, because their actions depend on many different motives, which are not all evil.