“The corruptibility of the superego,” a concept originated by Alexander in 1929, has received limited attention in contemporary psychoanalytic literature, but in certain contexts, Alexander's conceptualization remains relevant. In this article I incorporate it into the framework of modern conflict theory, with a focus on the importance of unconscious fantasy. Using clinical material from the analysis of a man who was a replacement child who suffered from depressive, narcissistic, and masochistic features, I demonstrate the significance and usefulness of the superego's corruptibility and its limitations for treating some patients with superego pathology. Some of the challenges associated with treating superego pathology, including transference and countertransference dynamics, and the negative therapeutic reaction, are also addressed.