Irken

"These Irken bastards came to our planet. I think they're just in time for Organic Sweep or something else."

--Su Ji-Hoon, Coming in Peace

The Irkens are an imperialistic race of green-skinned humanoids from the planet Irk. The basic goal of the Irken race is total universal conquest; they mostly attain this feat with the aid of their vast armada, which aids in planetary destruction (or because they have allies with the Coalition of the Red Star, a planetary change) via a sort of final attack called the Organic Sweep.

Appearance and Biology
Main article: Irken Biology

Irkens bear a similarity to the humans' archetypal concept of aliens as "little green men" - they have light green skin, sport a pair of angular antennae atop their hairless heads, and have solid-colored eyes (usually ruby). They are generally somewhat short in comparison to humans, usually approximately three to five feet tall. A unique aspect of Irken biology is the PAK device that is attached to every Irken's spine at birth, and serves not only as an ever-present Swiss Army knife, but also a backup brain.

Irken Society
Main article: Irken Society

Irken society is best described as a hierarchy based solely on height; tall individuals are respected and usually assigned to high-ranking jobs. Short individuals, such as Zim and Skoodge, on the other hand, are looked down upon both figuratively and literally, and are usually assigned to menial labor. The tallest living Irken (or Irkens, should there be two of the same height) is selected to rule the Irken Empire as the Almighty Tallests.

As Hobo 13 reveals to the viewers, the Irkens have the exact same number system as humans. This is demonstrated when Bob is crunching the numbers on his calculator.