Several alien races have been introduced on Falling Skies.
Introduced in Season One:Edit
- Skitters: Originally thought to be the alien species responsible for invading Earth, the Skitters are a race under the control by the Overlords. Their home-world was subjugated by the Overlords and the Skitters were harnessed just like the children of Earth. Some Skitters have been able to overcome their controllers and plot rebellions against the Overlords.
- Harnesses: Are parasitic creatures which allow other races to completely control the wearer. It was not known that these were their own creature (and not just a piece of bio-mechanical equipment) until Season 2. Their real names are chemlocks according to Red Eye, the leader of the Skitter Rebellion. In Season 4 a new form of portable harness is being used by the Espheni to mutate adults into humanoid mutations similar to skitters.
- Espheni: The force behind the Invasion of Earth. The Espheni were introduced late in Season One. They have a very large intellectual capacity, able to control many harnessed individuals at once using merely their mind. In the Season 2 finale their actual name was introduced: "Espheni".
Introduced in Season TwoEdit
- Crawlies: Small creatures under the control by the Overlords and used to flush people out of narrow spaces as they can eat through metal. They have only appeared in one episode, when they use Jamil Dexter's body as a Trojan Horse and crawl out when the others are near. They were mentioned in another by the end of Season 2.
- Eye Worms: Small bio mechanical parasites that hide in or near the skin covering the eye of their hosts. Their true purpose is unknown but appear to be designed for surveillance and turning their hosts into sleeper agents. The Espheni have used multiple human hosts, first being Tom Mason, second being Hal Mason then Lourdes. The Eye Worms are able to be removed with the smallest appliance, however learn how remove them without harm in Season 3 with the Volm technology. Lourdes was seen to have hosted multiple eye worms and were under control by the Espheni, causing her to kill multiple people and cause her extreme pain until Alexis removed them.
- Volm: Arriving at the very end of the final episode of season 2, Volm are a race which claim to have been at war with the Espheni for longer than most Volm have been alive. The Espheni took their planet long ago. In Season 3, the Volm set up a base by Charleston, South Carolina, and are building a weapon to take down the Espheni power grid for reinforcements to fight the Espheni. In Season 4 the greater Volm forces leave Earth to engage the Espheni who in the meantime attacked their young and brood mates, leaving only a few scouts remained on Earth and at the end of Season 4 are now working to find Tom Mason. The Volm, particularly Cochise, aid in the destruction of the Espheni Power Station and aid the Global Resistance in their final push against the Espheni in Washington, D.C..
Introduced in Season Four Edit
- Black Hornets: Skitters once part of the Rebellion, but now captured and controlled into mindless drones. They have the ability to fly. They are massive in size and covered in engorged, tumor-like growths. Unlike their less-evolved kin, they have blue eyes, have four wings, and an elongated tail. Their tails are prehensile and incredibly strong, allowing them to effortlessly carry objects as big as a full grown man into the sky.
- Dornia/Great Enemy: First race enslaved by the Espheni and the basis for the Skitters. The Volm believed them to be extinct, but at least one member of the race survived and fought a millennia-long war with the Espheni, wanting revenge for the destruction of its species. The Dornia drove the Espheni from their home galaxy and have been chasing them across the universe, with the Espheni conquering planets to fuel their war machine against the Dornia. After the Espheni Power Station is destroyed by Alexis Glass-Mason at the cost of her life, the Dornia survivor is able to enter the Solar System and rescues Tom Mason from an adrift Beamer. The Dornia appears to him in the guise of his first wife to communicate with him and guides him against the Espheni. This Dornia explains that it is the last of its race and wants to honor its dead race by destroying the Espheni for what they did to the Dornia. The Dornia supplies Tom with a weapon which when used on the Espheni Queen, will wipe out the Espheni and promises to guide him as much as it can in his journey to the queen. After Marty modified it to be non-lethal to humans, the weapon has been proven to be effective when used against the Espheni clone of Alexis Glass-Mason.
Introduced in Season Five Edit
- Waspers: The bugs are mutations by the Espheni using parts from skitters, Espheni, hornets and humans. They are in use by the Espheni, a weapon that travels in swarms, and have been scattered around Earth currently, with an unknown goal, possibly to kill the last trace of resistance fighters. They have successfully devoured and killed two fighters, Sara and Ryan.
- Espheni Queen: Mentioned in Hatchlings, this species appears to be a leadership hierarchy amongst the Espheni race. In Stalag 14th Virginia, dozens of Overlords are seen bowing before an immense shadow approaching them, and the Higher Being is briefly seen. The Volm seem to be slightly aware of their existence, but believed them to be myths until Ben Mason witnessed one in the Shadow Plane. The being is later revealed to be the Espheni Queen who's presence on a planet only occurs when the Espheni believe victory to be at hand and change from invasion to occupation.