From Alien to Arrival, these sci-fi movies never loosen their grip, turning ideas into nonstop tension that pulls you through ...

We asked our readers to name their favourite films in the sci-fi genre – and these were the titles that came up most often.

While there are a lot of sci-fi films that could go on this list (and really, any sci-fi film is worth watching more than once) there are some films that are just perfect for multiple viewings. Here ...