Invader Meep is similar in appearance to Zim, save for the scar on his face (earned in the Battle of Mushroom Kingdom), his greater height and the fact that his eyes are a somewhat darker shade of red.
Unlike most invaders, Meep prefers to wear a variation of the typical Irken uniform, with a black tunic, red sleeves and leggings, and gray collar and shoulder bands.
Invader Meep is technically a defective, although the malfunction in his PAK resulted in him developing an increased intelligence and an affinity for weapons technology. Because Invader Meep is a fan of electronic entertainment and random humor, he was impressed with Zim's robot assistant, GIR.
During the battle of Mushroom Kingdom (in which the notoriously stupid Mushroom people were aided by the vicious Space Pirates), Invader Meep was mortally wounded. With his life rapidly fading, he barely managed to transplant his brain into the body of a recently deceased comrade, whose PAK had been knocked off. Fortunately, Invader Meep's brain quickly adapted to its new home, and he was able to attach his PAK as well. Ironically, he was despised by the Tallest prior to his ordeal in Mushroom Kingdom, but became revered by them afterward due only to the superior height of his new body. The only remaining sign of the whole affair is a ropy scar on Meep's left temple.