Chitauri

The Chitauri are characters in the 2012 upcoming action film The Avengers. They are part of Loki Laufeyson's Army.

The Avengers
The Chitauri are a lethal race of alien cyborg-like creatures, and they're on Thanos' service. When the Mad Titan allies himself with the exiled god Loki Laufeyson, the Chitauri are granted to him as his personal army to conquer Earth and gain the Tesseract.

Once gained the Tesseract from S.H.I.E.L.D., Loki is able to open a portal to the Chitauri's world, thanks to the help of a brainwashed Erik Selvig. The Chitauri immediately start to wreck havoc on New York, attacking civilians and destroying buildings and streets. The army and the police forces aren't able to do anything about them. Soon after their arrival, anyway, The Avengers appear, and a major battle begins.

Not expecting such a resistance, the Chitauri are initially overwhelmed, but soon their number encreases so much that the superheroes find some difficulties in containing them. Captain America takes command of the Avengers as well ad the police forces, and thanks to his command, the Avengers' powers are properly used and displayed to face the menace. Eventually, the Government decides to blow up Manhattan with a nuclear bomb in order to contain Chitauri's invasion, much to Nick Fury's dislike. Fury orders Iron Man to intercept the bomb and dispose of it, and Stark takes it to the portal and blows up Chitauri's Mother Ship, thus cutting the link of the aliens' collective mind and killing them all.