Vortians

The Vortians are a highly intelligent race of alien scientists that inhabit the planet Vort and its colony worlds.

Biology and Appearance
Vortians have hocks on their legs which lack conventional feet and seem to be pointed at the end. They also have curled horns on the top of their heads, which can move, similar to an Irken's antennae. They have tiny eyes of a single color, and ave above regular sized heads. There doesn't seem to be much difference between the males and females. They can also reproduce sexually, and some have reproduced with and married different species. Vortians resemble goats in some ways, just as the Irkens resemble insects.

The inside of a Vortian's mouth is very similar to an Irken's, with zipper-like teeth and a worm-like tongue.

Vortians may seem to be carnivorous, or meat-eating. The only Vortian food shown in the show are "Vort dogs" sold at Shloogorgh's Flavor Monster, which are hot dogs presumably made of a meat like Earth's hot dogs and prepared in the same manner. Vortian teeth are also sharp and jagged, suggesting a carnivorous diet. Vortian tongues are segmented similar to Irken tongues, and have similar taste buds.

Most Vortians are rather short, about the same height as Irkens. It is unknown if their society is based on height. It may be that Vort's leaders were instead elected in a republican or democratic governance system, like most of Earth's.

History
Vortians are responsible for most of the Irken's technology resources, for two reasons. The first reason was because, in the past, the Vortians were allies of the Irken Empire and supplied advanced military gear, and the second reason is because of its failed attemt at conquer by Invader Larb, and the resulting Irken/Vortian War. They were now forced to supply military gear. Not all Vortians are prisoners; some have escaped and can be seen briefly on planet Foodcourtia. Eric the Blob mentioned that he had installed similar security systems to the one in Shloogorgh's Flavor Monster in Vortian prisons, but they were discontinued after multiple Vortian prisoners escaped by "hiding deep in garbage cans". This could explain Lard Nar's freedom and could pose as an excuse as to why there may be already-free Vortians.

Vortians created devices such as The MegaDoomer and Minimoose. However, it was suspected the Vortians had shown small signs of rebellion by purposely flawing their creations. For example, the Vortian-designed MegaDoomer oddly cloaked itself, but not its user, and, for obvious reasons, Minimoose isn't any more reliable than GIR as an evil minion/sidekick. Also worth noting is that Vortian Prisoner 777, an acquaintance of Zim, was willing to hand over the Massive's schematics, even though he knew, and warned, that it could have infuriated the Irken Armada. (He was later freed by Dib after the war ended).

The only piece of technology shown during the series of purely Vortian design is the resisty's ship.

Ever since Zim ascended to the Irken throne, the Vortians' alliance with the Irkens has been completely restored through peace initiatives, and as a first gesture of peace on Dib's side, several Vortians were freed to help rebuild Earth after the attack by the Irken Armada there. Several Vortians were even invited to Zim and Gaz's wedding and their coronation.