Jaws (1975)

At 124 minutes this is one of the few picks past the two-hour mark, and it earns the exception. The shark stays mostly out of sight for much of the movie, so the dread comes from yellow barrels, a two-note theme and three very different men stuck on a small boat together. It plays like an adventure as much as a monster movie, scary rather than gory for most of its length. It was the first movie to take more than $100 million at the US box office and is credited as the first summer blockbuster, yet it never feels like homework.