Espheni

The Overlords are the alien leaders in the series Falling Skies. They were previously called Slenders by fans.

Appearance
The Overlords are tall, thin, bipedal grey aliens. They tower over humans and Skitters. They look like dolphins from the chest up, leading the resistance fighters to call them "fish-heads." They have very skinny arms that go from their shoulders to their knees. Their eyes are mammalian in appearance and they do not appear to have noses, rather, nose slits like snakes. They are unable to fight and they need a harnessed child in order to interpret human speech, as they have little understanding of it. They lack fighting capabilities.

In the Series
It is revealed near the end of the season 1 that the Overlords are the apparent masterminds behind the invasion of Earth in Falling Skies. They are first seen in Episode 8 by Resistance fighter of the 2nd Mass Tom Mason, Hal Mason and Captain Dan Weaver on a scouting mission in the city. Tom believes that the aliens are only now showing themselves because they believe they are safe and have won.

It is also known through examination of a Skitter corpse that the Skitters are also slaves due to the discovery of a harness buried in the corpse's spine. The resistance concludes that the Overlords use the Harness to generate the Skitters as a form of slave labor and then shock troops once the victim has been transformed.

In the series finale the Resistance is able to launch a powerful counterattack against the invaders. After discovering the Skitters and Mechs are linked through a radio frequency they come up with a jamming frequency that they use to disorientate and repel an attack on the Resistance base. This leads to a mass retreat by the alien forces back to the structure in the city. Tom believes that they have managed to confuse and possibly even scare the aliens. Taking advantage of the retreat Tom is able to fire a missile at a fleeing ship that crashes into the Alien structure causing significant damage.

As Tom and Weaver are returning to the Resistance meeting point they are confronted by former comrade Karen; who has been harnessed weeks ago. Approaching her cautiously Karen addresses Tom and says that the Overlords brought her here because they don't understand. An Alien ship with a Overlord arrives and Karen explains that they did not anticipate such resistance from a less advanced race than their own. This has interested them and they now want to talk. Weaver and Tom are furious at this revelation that the aliens are only now acknowledging their victims when they fight back hard.

It is soon revealed that the aliens want specifically to speak with Tom since his son is still under the influence of the Harness conversion process, due to it being removed too late. In exchange for going with the aliens Tom's son would be released from the process; with no other option Tom is forced to leave with the aliens ending the first series.

At the start of the second series Tom is revealed to be one of many the aliens have "invited" aboard there ships. After enduring torture for 3 months Tom is brought before an Overlord to here a proposition. Humans will be allowed to live in neutral zones in exchange for the surrender of the Resistance. Tom however sees through this has nothing more than a prison camp; arguing with the aliens over their view of humanity being violent and savage when they attacked mankind is such a violent manner. Tom refuses along with the other captives who are released to a firing squad with only Tom surviving.

Purpose
As of yet the aliens motive behind the unprovoked invasion is yet to be revealed.

Technology
The Overlords possess highly advanced, invasive, and destructive technology which they have employed in their invasion of Earth. This includes:
 * Air Ships: The Alien equivalent of Earth fighter jets used for transport and also bombing runs on the Resistance when they were still in the city.
 * Mechs: Robotic soldiers used to crush any resistance in the initial invasion and to hunt down any survivors after a foothold is established.
 * Harness: A truly invasive and horrifying device used by the aliens on abducted children. Initially used for mind control it eventually mutated the wearer into a Skitter adding to the Overlords' forces.
 * Crawlies: A blue spider-like creature that can infest bodies of animals (including humans) and use them like Trojan Horses. They then burst of of their chest and attempt to repeat that process.

Interactions with Humans
Initially the aliens held little regard for humanity; viewing them as vermin and ordering their forces to eradicate and enslave any survivors of their attack they came upon. They are disgusted by humans killing each other yet have no qualms with murdering another race to suit their needs. They initially had little concern for the human resistance; apparently confident in the fact their forces will deal with them soon enough.

When humanity's resistance efforts however prove to deal a significant blow to the alien forces they are intrigued. They send a representative and a human slave as a mouth piece to intercept Tom and Weaver and threaten reclaiming his son in return for him going with them to "Talk".