Directors who kept a personal voice inside Hollywood's studio system

[Gregory_C]

I'm researching the studio system of Hollywood's Golden Age for a documentary project, and I'm fascinated by the immense creative output that existed alongside the notoriously restrictive contracts and moral clauses imposed on stars by the major studios. Figures like Bette Davis and Olivia de Havilland fought legal battles for creative freedom that changed the industry. For film historians or enthusiasts, which directors from that era do you feel managed to produce truly personal, artistic work within the rigid factory-like system? How did the Hays Code actually force filmmakers to become more inventive with subtext and implication, and are there any lesser-known films from the 1930s or 40s that you believe exemplify the hidden complexities of that period beyond the iconic musicals and noir?