9. Sleep Chamber Malfunction - 2001: A Spacey Odyssey
In 2001: A Space Odyssey, a crew of pilots and scientists are sent on a mission to explore a mysterious artefact on the moon. Their ship, Discovery, is programmed with a sentient computer called HAL 9000, who assists the passengers to the best of his ability.
Over time, HAL becomes convinced the humans on the vessel are hindering the mission and thus, decides to eliminate them. While Poole goes for a space walk, HAL cuts off his oxygen hose, asphyxiating him to death. When Bowman heads out of the ship to rescue Poole, HAL locks the door to prevent him from returning.
With Bowman and Poole out of the way, HAL turns his attention to the remaining three crew members, who are in suspended animation. By deactivating the life support system, each of the passengers suffocate to death (while they are fitfully imprisoned in their coffin-shaped chambers.)
What makes this moment so unnerving is how the trio have been asleep for their entire mission, meaning they would have no idea what was happening to them in their final moments. Despite the fact we never see these crewmembers' faces clearly or get to know them, you can't help feeling sorry for them.