Harvester (Independence Day)

These aliens are a race of sapient, spacefaring creatures which travel from planet to planet like a galactic swarm of locusts, devouring each world's natural resources before moving to the next one, bringing their entire civilization in massive ships.

Overview
Physically, they are no more durable than a Human, but they do possess far superior technology, including enormous fleets of ships; defense fields to prevent missiles from reaching their ships' hulls; highly destructive weaponry and protective biomechanical suits.

The aliens have a slender, quasi-humanoid body with three-jointed limbs and only two digits on their hands and feet. Their head is enlarged. They have large, pupil-less eyes (or eye-like organs) and a number of long, grasping tentacles protruding from their suits' backs. Lacking both ears and vocal chords, they communicate using a sophisticated form of telepathy. They are also able to control other beings, at least partially, by attaching tentacles to their necks. They apparently do this in order to communicate with non-telepathic species.

They travel around the galaxy in a single, massive Mothership that is around 550km (341.75mi) in diameter. This ship can deploy numerous smaller, city-sized spacecraft. When invading an inhabited planet, the aliens' military tactics consist of large-scale attacks, destroying the major cities around the globe simultaneously and then heading to the next largest, presumably going on until there is nothing left. This species breathes oxygen and requires similar environmental conditions to humans, which is possibly the reason why they became interested in Earth in the first place. Although a single alien ship crashed on Roswell in 1947, the actual invasion only started in 1996. At the end, the aliens were defeated and possibly driven to extinction thanks to the creation of a computer virus which temporarily removed the alien ships' shields, followed by a devastating nuclear attack on their orbiting motherships.

Technology
The technological standpoint of the aliens is clearly far more advanced to those of the humans and even their past enemies. They have mastered the usage of energy based weapons, deflector shields and even city destroying spacecraft. Despite their technological advancements, the computers have not been outfitted with anti-virus software which is what caused them to lose against the remaining human forces. The virus caused a major flaw in their systems which crippled the shields on all their vessels, even their mothership.

Behind the scenes
The aliens were designed by Patrick Tatopoulos. The movie was created by Roland Emmerich and Dean Devlin, the same creators of the Stargate franchise. The creators stated that they wanted to create a different sort of alien invasion. While in most films the invasion starts furtively, with the aliens hiding in the countryside or secretly assimilating people with spores; the aliens from Independence Day are confident in their superiority, and start off in a real large scale assault, literally destroying all the world's major cities.

Two sequels are currently in the scriptwriting process, which may indicate that the world will once again (or, should we say twice again?) have to face these alien menaces. This would presumably also prove that the "ID4 Aliens" are not extinct quite yet.