Mummy Issues

What is the best horror film based on fucked up relationships between a mother and her son? Psycho is perhaps the most famous example, but films like Maniac have expanded upon the idea of deeply damaged, disturbing relationships between mother and son. The theme surfaced more recently in the successful We Need to Talk about Kevin, and we want to know your thoughts. What are some of your favourite examples of these relationships in horror? How would you want them to be approached in future? What works about them, and what doesn’t?