The Klerg are evil aliens that hate Klooton and try to attack it. They are the reason for Marvin to be sent to Earth to protect himself until the Klerg are crushed. Klergs made only one appearance in Big Time Marvin when they impersonate Big Time Rush and another one makes an appearance and it is referred to as "The High General", "Mommy" and "Mom" by the Klergs who impersonated BTR. The four klergs who impersonate BTR later are defeated when Marvin sprays a tank of helium at them, weakening them and defeated them, as helium is the Klerg's weakness and is referred as "kryptonite to the klerg." by Marvin.They serve as the overall primary antagonists of the series.