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H. G. Wells introduced the alien's come to destroy the earth, planet wars, initial contact, and different species themes in 1898. Other authors have written science fiction about aliens during the same period. Robert Potter published The Germ Growers in 1892.
It is about a concealed invasion wherein the invaders cloak themselves to look human, use mind-control, and teleportation. They create a deadly disease to help them control the earth. Potter could have been credited with introducing four well-known tropes: unknown deadly disease, mind-control, teleportation, and aliens camouflaged as people. But his novel wasn't popular.
The allegory in the story involves fallen angels and a pure angel that opposes them. Maybe the allegory put people off, but symbolism is a legitimate writing element. Though this element puts it into a mixed genre of science fiction and fantasy.
When Wells wrote and published War of the Worlds (1897), the invasion story was already in vogue. The theme and plot concerned other countries invading Britain. It normally involved their long time allies/enemies France or Germany. He turned the idea on its head with an alien invasion from outer space. Space alien invasion stories became very popular in short stories, novels, and movies.
The Invasion of the Body Snatchers ( 1955) by Jack Finney plays on the trope of aliens looking like humans in order to destroy people, which is part of their reproductive process. Seeds infiltrate from space and duplicate humans using plant type pods to grow the replica. The sleeping people crumble into dust. The aliens lifespan is five years.
They only reproduce by pod. So, if they aren't stopped, they will demolish earthlings and go to another planet and duplicate the process.
Above Donald Sutherland is screaming the horrid pod scream in the 1978 film version of Invasion of the Body Snatchers. It is a redo of the 1956 film.
In The Puppet Masters published in 1951, Robert A. Heinlein tells the story of a parasite alien invasion that controls people's minds. They are slugs that fasten to their victim's back and control their nervous system. The enslave trope is applicable in this scenario.
World War is the name given by aficionados to a series by Harry Turtledove. These science fiction alternate history novels happen during World War II, so the earthlings have to unite against a common enemy: aliens. The alien race is reptilian. their rate of change and development is slow. They had scouted out earth during sword battling days, but come back later to find a more advanced technology that they didn't expect. They ponder invading, decide to go ahead by order of Fleetlord Atvar. The battle is on.
The books in Turtledove's World War series are Tilting the Balance, Upsetting the balance, and Striking the Balance. In the Balance.
In the Balance: An Alternate History of the Second World War (Worldwar, Volume 1)
In Death Ground by David Mark Weber and Stephen White is a military science fiction novel in which alien bugs cultivate ranches of other species to eat them. The Shiva Option is the sequel.
They come to earth to invade it and annihilate, control, or eat humans. These are the main alien tropes, and they overlap sometimes, but they are perennial favorites that writers and readers return to for a science fiction thrill.
The Classic War Of The Worlds
The Germ Growers-Robert Potter
The Body Snatchers
Happy Peninsula Digital Painting