With two musical notes, director Steven Spielberg had a villain. In 1975, summer thriller Jaws hit theaters, terrifying audiences and introducing an entirely new concept of Hollywood film: the summer blockbuster. Based on Peter Benchley's novel of the same name, Jaws was the highest-grossing film in history, until losing the accolade to Star Wars two years later. The flick was regarded as not only a feat in Hollywood marketing, but also in special effects. Spielberg's mechanical monster was so effective, it became a p.r. nightmare for shark researchers, who are still fighting to clean up the creatures' image more than 30 years later. In reality, there are usually fewer than 63 shark attacks on humans worldwide per year — in fact, pigs kill more people each year than sharks do — but that fact hasn't stopped us from nervously watching the waters beneath our feet.