Science fiction movies have always been a mainstay of Hollywood but over the years, there have been many that were criminally underrated when released and have largely been forgotten over time. For every blockbuster such as Star Wars and E.T. The Extra-Terrestrial, there’s a gem of a movie such as Gattaca that has been left in the dust. Even some science fiction films that are considered classics now—such as Blade Runner—were not appreciated when first released, but rather built up a loyal following over many years. A lot of science fiction films need time to find their audience and with that in mind, here the top 20 underrated sci-fi movies of all time.