20. Sidney Lumet
Known for his impeccable craftsmanship, Sidney Lumet created some of the most endearing films of his era, consistently turning out quality film year after year for much of his career. Lumet became one of the first directors to successfully transition from TV to Movies when his 1957 film 12 Angry Men became one of the most acclaimed American films of that year and one that has become one of the most fondly remembered films of that era. The success of the film launched one of the most consistently excellent careers of any Hollywood director as over the next few decades he turned out many great films including Fail-Safe, Dog Day Afternoon, Network, and many, many others. Lumet was always well liked by his actors due to his flexibility regarding how they portrayed their characters and he would often take actors aside privately and listen to their advice. Many people in the film industry considered him one of the most cordial directors they ever met, which in addition to his abilities make him one of the most beloved of all directors by his contemporaries. His films were energetic and infused with a sense of realism and social justice. In his later life, he wrote one of the most well regarded books about the practical aspects of filmmaking which remains an invaluable resource for many aspiring directors. Lumet is in many ways the archetypal director of classic Hollywood, someone with talent, ambition, and someone who was also by all accounts an all-around great guy as well.