Irken Empire

"The Irken Empire, an aggressive expanionist empire, was a wealthy and well-known empire. I remember the time when the Irken Empire is getting ready for its expansion, and with that, since they are being allied with China, North Korea, Russia, and their allies, they are ready to take over the world, just in time for Operation Impending Doom III. I fear that my village people will be enslaved by the Irkens, the Chinese, the Russians, the North Koreans, and their allies."

--Su Ji-Hoon, Coming in Peace

The Irken Empire is an aggressive expansionist force headed by the war-like Irken race. The Irkens are bent on galactic conquest and, with the aid of their massive armada, they may actually achieve this goal. The co-ruling emperors of the Irken Empire are the Almighty Tallest, Red, and Purple.

In When the Cold Breeze Blows Away, they were aggressive to both the Grand Alliance and the Coalition of the Red Star, but with the Treaty of Sapporo, the Irken Empire is eventually allied with the Coalition of the Red Star in their quest of total world domination under Operation Impending Doom III.

History
The general history of the Irken Empire is mostly unknown, but by the time of the series is reasonably extensive, and both powerful and rich enough to engage in further plans for conquest. Several allied species affiliated themselves with the Irken Empire, and numerous others were already subservient to them, serving in a number of single-task roles as each planet is given a singular purpose in the Empire.

When Zim was born, he caused two periods of horrible blackouts on Irk.

During Zim's tenure as a scientist on Vort Research Station 9, then-Tallest Miyuki commissioned the Vortians for the design, and later building, of the Massive, shortly before being devoured by an infinite-energy-absorbing monster blob. The next Tallest, Tallest Spork, was also devoured by this same creature, when the monster returned the next day.

At some unknown point, the current Tallest ascended to the position, and eventually oversaw the beginning of Operation Impending Doom I. This plan was foiled by Zim, who proceeded to accidentally destroy a portion of Irk with a commandeered a Frontline Battlemech, blowing up the first generation of Invaders and a portion of the Irken military.

Shortly after Zim's re-encoding and banishment to Foodcourtia, the Tallests initiated Operation Impending Doom II, which following Zim's re-banishment to Earth, experienced mostly success, conquering a number of worlds including Blorch and Vort.

In the cancelled episodes of Invader Zim, the battle for Meekrob was supposed to blow into all-out war against the Irken Empire when Invader Tenn was captured. The status of the Empire after this event, and Dib taking residence on Irk as a counter-Invader, is unknown.

Enemies
The Irkens are a bloodthirsty race, as Irkens have a superiority complex and feel a need to conquer other worlds. Because of this, the Irken Empire has many enemies.

The Resisty
The Resisty first appeared in "Backseat Drivers from Beyond the Stars" and it is an organization created to overthrow the Irken Empire, and the Resisty's members are presumably members of planets conquered by the Irken Empire. The Resisty attempted to pierce a hole in the Massive's sidepods, which is full of snacks, and the ship's one weakness. However, they failed in this task, and merely succeeded in lasering "RESISTY ROCKS!!!" on the sidepods (which was then washed off). They are later seen on the Irken snacking planet of Foodcourtia in "The Frycook What Came from All That Space" and they were scheduled to returned for the two part season finale and the TV movie "Invader Dib" presumably getting exiled to Saturn as punishment for planning genocide on the Irken race.

Meekrob
A common enemy of the Irken Empire is the Meekrob, a species made of pure energy. The Irken Empire and the Meekrob are currently in a war on their planet of the same name, but had Invader Zim continued everyone would have seen more of this war.