Almighty Tallests

The Almighty Tallests Red and Purple are major antagonists of Invader Zim. They are the leaders of the Irken Empire that are chosen for their height.

In the show, they both despise Zim, a young, ambitious Irken whom they sent to the previously thought to be fake planet "Earth", only to realize that Earth was actually real. They often appear in episodes where they reluctantly check up on Zim and his "mission". They first appeared in "The Nightmare Begins."

Biography
Before Red and Purple became the Tallest, Almighty Tallest Miyuki and Spork were the leaders before getting killed by one of Zim's experiments, according to an unfinished episode.

In the series, the Almighty Tallest make occassional appearances, usually being contacted by Zim. Some episodes including them even have the Tallest play a major role.

In the 2019 Netflix film Invader ZIM: Enter the Florpus, Zim becomes distraught upon learning that the Tallest weren't going to come anywhere near Earth. After Dib inspires Zim to formulate another plan to take over the planet, the Tallest and their fleets are sucked into a blackhole with their final transmission implicating that they were burning in a hell-like dimension for eternity, thus ending their conquering of worlds for good.

Personality
The Red Tallest is very cunning and calculating, tricking Zim into going to Earth in the first place. The Purple Tallest is rather idiotic and slow.

They both love to eat junk food and like sending young Irkens on missions to other planets. Both are the true main villains in the series.

Trivia

 * It was revealed in an interview with Wally Wingert that there was going to be an episode where it was revealed that the Tallest weren't actually tall, but were smaller Irkens wearing robot suits to make them appear taller.
 * Purple was voiced by Kevin MacDonald, who also voiced another (albeit far more benevolent) alien, Pleakley from Lilo & Stitch.