Few horror directors understand true terror the way Alfred Hitchcock did. After all, he is better known as "the Master of Suspense," and his six-decade career gave us a whopping 50 feature films. His most terrifying films include Rebecca (1940), Spellbound (1945), Dial M For Murder (1954), Rear Window (1954), Vertigo (1958), and of course, Psycho (1960). Psycho's terrifying shower scene is still referenced and considered a major source of inspiration for horror filmmakers today, and it's also the reason we double bolt our bathroom doors.