Don't be fooled by her passive aggression. Mama will sting you like a bee. 

Imagining herself above the laws of a secular, civilized world, Sister Summersisle leads a community of neo-Celts who take kindly to, among others, human sacrifice. 

Ellen Burstyn brings Summersisle's shaky morality to fiery photo-reality in The Wicker Man, the 2006 remake of the film of the same name. Christopher Lee made a killing as the male imagining of the character in the original, released in the same year as The Exorcist, which starred Burstyn. 

Once a horror queen, always a horror queen...