I have a couple. Piper Laurie as Carrie's mother is phenomenal. Not even Julieanne Moore could top that.
Gena Rowlands in A Woman Under the Influence. Such a beautifully nuanced performance that hints at the possibility that her social surroundings are crazier than she is.
Alicia Silverstone in The Crush. I had a major thing for her.
shareAmber Heard in All the Boys Love Mandy Lane (2006)
shareAn only slightly crazy performance but a sweet movie by the late Jon Demme, is --
Melanie Griffith - Something Wild
She's pretty crazy until her crazier ex (Ray Liotta) shows up. Suddenly she's not so crazy anymore.
Gloria Swanson in Sunset Boulevard.
shareAnn Blyth played a pretty good psychopath in Mildred Pierce.
shareHere's an oldie -- Olivia de Havilland in The Snake Pit.
Piper Laurie was scary-creepy in Carrie.
Glenn Close as Alex Forest - Fatal Attraction
Blanche Baker as Ruth Chandler - The Girl Next Door (2007)
Jessica Walter as Evelyn - Play Misty For Me
Kathy Bates as Annie Wilkes - Misery