The sci-fi movie The Day the Earth Stood Still has had two incarnations: the 1950's classic and the 2008 remake. Their combined messages, warning humans, are relevant to the COVID-19 pandemic we are now living through.
In the original (starring Patricia Neal and Michael Rennie as the alien Klaatu), Klaatu tells Earth's scientists that he represents an interplanetary organization that created a police force of invincible robots like Gort, the one standing guard at the spaceship: "In matters of aggression ... have absolute power over us." As an example of the alien's superior technology's ability to destroy life on Earth, Klaatu and Gort simultaneously stop all activity on the earth. Klaatu's parting words: "Your choice is simple: Join us and live in peace, or pursue your present course and face obliteration. We shall be waiting for your answer."
The backstory for the original version was the creation and use of the atomic bomb and its potential to annihilate life on the Earth as we know it. The backstory for the 2008 remake (starring Keanu Reeves as Klaatu and Jennifer Connelly) has an explicit environmental theme: global climate change. In the 21st-century version, we humans are destroying the Earth's environment, and the aliens have come to save the Earth and its species, excluding us. All electrical activity on the Earth is simultaneously stopped to warn us to change our behavior as the alien stops a pandemic-like swarm.