Grand High Witch- The Witches
Not all witches are malicious, but this one definitely is. Anjelica Huston brings the Grand High Witch character to life on screen by mastering 4th wall breaking stares directly into the camera without feeling contrived. Think about how scared you were when you watched Funny Games for the first time, then magnitize all of the 4th wall breaking scenes and that's what you'll get from watching The Witches in full.
Mathilda- Léon: The Professional
Natalie Portman was built for the big screen since she was a child. Her performance in The Professional was a defining moment for her flexibility as an actor, as well as her skill overall. That, and she carried a real gun around set at 12 years old and people trusted her enough to not do anything funky with it, which is a huge test of maturity.