The Irkens are an imperialistic race of green-skinned humanoids from the planet Irk.

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.