The War of the Worlds began as a science fiction novel by H.G. Wells in 1898, and has had people seeing lights in the sky ever since. If you don't know, it's about martians who for some reason invade earth, and eventually catch colds.
In an idyllic late-Victorian english town, (Woking, Surrey, England to be specific) a bunch of martians land, and begin an invasion of earth. After the martians make an attack in their true forms (think bear-squids), and are repulsed by the atmosphere, they retreat and climb inside huge fucking devices called tripods. This is armed with their heat ray, which vaporizes everything it touches, (think of Thermite that you can shoot) and quickly destroys any puny resistance the human race can muster. The narrator flees, along with the rest of England, which is definitely a first for the country.
The martians quickly take over all of England, spreading with them a red weed. death, and destruction. The intent of their invasion is still not clear. Aside from, oh yeah, drinking people's blood. But anyway, the narrator finds some crazy dude to hang out with, who eventualy gets eaten by the martians after he won't shut the hell up. There's one in every bunch.
Eventually, the narrator wanders to London, to find it deserted. He soon gives up hope of ever returning to a normal life, and decides it better to simply run headlong into his fate. Surprise! The aliens have died. It's not specifically stated what they died from, just that they died of sicknesses to which they had no immunity.
Thus ends the story that would, among other things. inspire awe in many literary enthusaists, scare the shit out of nearly 6 million people in 1948, and allow Tom Cruise to make yet another unnecessary movie.
Most of later science fiction. Anything with aliens or alien invasions in it are somehow similar or inspired. Notably:
Yes, George Lucas drew extensively off of H.G. Wells' story for inspiration on Star Wars. Alien designs, their behaviors, language barriers, even the weapons to some extent were based off the Martian's weapons. Apart from that, the vehicles, particularly the AT-AT and AT-ST were helped along by the Martian's tripod design. Behold:
Notice the similarities. All three (well, maybe not the AT-ST) are huge, menacing, and armed to the teeth. Also, seemingly invulnerable to conentional attack. Unfortunately for humanity, no one thought of tying cable around the Tripod's legs. And now, since you knew it was coming:
After you realize that similarity, they start popping up everywhere. Now, for more obvious ones:
Independence Day. Alien Invasion, utter destruction...failed attempts at retaliation. Hell, the alien fighter ships look nearly identical to the Martian ships in the 1953 War of the Worlds.
The Striders from Half-Life 2: An attack that can all but obliterate you, the three long legs, utterly terrifying...If you didn't see that coming, you clearly haven't been reading or seeing any of the pictures, or ever played Half-Life 2. In the latter case, stop, go to Best Buy, and get playing. Seriously.
Numerous Japanese Anime's have Mecha in them that are very similar to tripods.
The classic science fiction Book Ender's Game is a sort of role-reversal of War of the Worlds; Ender finds himself destroying another race in its entirity.
(more to come)