7. Silent Running (1971)
Cult sci-fi movie
Silent Running (which also happens to be a spiritual precursor to a film mentioned later on in this list) does, like
Cast Away, feature a few actors at the beginning of the movie, but once they've been offed, it's left to Bruce Dern and a few droids to lead the rest of the movie. As the eco-friendly caretake of a futuristic greenhouse (c'mon, it was the '70s), Dern goes against the direct orders of his superiors in order to preserve the Earth's last remaining greenery. If you like science-fiction, this is a must-see vision of the future, and one that has accumulated a dedicated fanbase even today. Bruce Dern is great as the solo protagonist, given that he's left to carry the weight of the movie on his shoulders, and this is one of the earliest examples of a Hollywood feature film that relies on a singular actor in a high-concept situation. Sure, it's dated a ton, and there are points at which the movie fails to live up to its premise, but as a science-fiction yarn and as a one-man show, it makes for essential viewing.