Kate Daniels/YMMV

• Complete Monster - the audience of the Midnight Games seem to be this, as they enjoy watching warriors kill each other in particularly slow, painful ways; some of the participants fit the trope as well, but the crowning examples have to be the Reapers who pour molten electrum - IE shapeshifter Kryptonite - on Derek's face after beating him within an inch of his life and embed his body with some Magic Rocks that prevent regeneration. They'd like to do similar things to every shapeshifter, because they hate humans and beasts as it is, but find a combination thereof to be particularly disgusting.
  • Erra fits this bill. She doesn't deny it when Kate calls her a psychopath (although she has to look up what the word means). When her children annoy her she kills them and pilots their undead bodies. She once "threw a hissyfit and blew up Bablyon", enjoys scaring crowds, just cause, and she tells Kate that because she and Roland are immortal, one human death doesn't mean anything to them so Kate shouldn't whine about Roland killing her mother. Ouch.
  • The Lighthouse Keepers, who are willing to kill thousands of innocents in order to achieve their fanatical anti-magic ends.
• Magnificent Bitch - Aunt B, especially in the fourth book.