The Kroloteans

The Kroloteans are small aliens from the planet Krolotea whose whole culture is built around stealing, and they always move in groups. They are short and scaly with horn-like points on their heads and eyes with three pupils, and their own language, Krollish, sounds like shrieking to humans. In Young Justice season 2 they are behind an alien infiltration of Earth that the Team and the League hunt down.