There is not much known about the Vreen, except that they originate from the planet Sectoid One and are the creatures of Lord Vringath Dregg, to whom they are subservient to as soldiers and service drones. The Vreen are not completely natural, but rather artificially bred organisms, whose bodies combine biological and mechanical elements.
Vreen are mostly used with the use of simple combat strategies, which aim to overpower an opponent by their numerical supremacy. Until they are needed, the Vreen spend their time in deep sleep in egg-shaped capsules. Vreen can fly, but they do not beat their wings, instead they let them circle like helicopter rotors on their backs; with this method they can also move in the vacuum of the space. Vreen however, are not provided with independent intelligence in their task as drones; if a leader is missing, they immediately return to their next floor without completing their actual task.
Lord Dregg orders the Vreen to destroy the Ninja Turtles, they chased them through space where they were defeated.
Vreen are insect-like aliens of slender, shaped as huge humanoid-like grasshoppers, with green chitin armor and a size of at least 2.10 meters. They're synthetic beings despite their organic look. Each Vreen have two pairs of wings, which can be spread and rotated as the blades of an helicopter. Vreen's left arm have a extendable tendril while the right arm has a laser blaster, which is fused with the rest of the arm.
When in attack mode Vreen's head collapses into its torso, making the orb in the cavity of its chest temporary eye. The V-shaped opening in it's chest is the orifice for an organic plasma weapon, which it mainly uses against large, immobile targets because it takes a few seconds to recharge.