Arquillian

Arquillians are a small sapient alien species from the planet Arquillia.

Overview
Arquillians are a small species. They wear a Human-sized mechanical suit, which is used for both protection and locomotion (also hiding their true form). Much of their energy goes to "drive" the mechanical humansuit, but they have a "autopilot" mode for making their life easier. To get the human suit to work, they have to download software programs to the brain. Too much information and the computer will have a meltdown, resulting in them divulging their true identity. They also possess a powerful weapon.

In the movie the MiB need to find the galaxy and return it to the Arquillians, who are threatening to annihilate Earth if it is not returned within a certain time period.

Trivia

 * A member of the Arqullian Royal Family was killed on Earth, resulting in its near destruction.
 * In the Men In Black Animated Series it is revealed Martin Luther King Jr. and John Lennon were Arquillians. This probably means Mark David Chapman and James Earl Ray were the Fmeks, sworn enemies of the Arquillians.