Grubs are a sapient species of stumpy insectoid beings possibly native to Planet Z. They were subjugated and enslaved by Emperor Zurg and currently work for him, performing a wide range of technical tasks and also acting as personal servants for the evil emperor.
The Grubs are usually described as being Zurg's equivalents to the Star Command's Little Green Men, although they lack a hive mind and are far less competent. Besides Grubs, Zurg's other subjects include robots and peculiar creatures called Brain Pods, which are merely brains and eyes placed in a robotic body and may have been Grubs too at some point of their lives.
The Grubs currently serve Zurg in Team Nefarious as his grunts and minions. A few grubs have even been reformatted into powerful humanoid warriors in gruesome experiments conducted by Doctor Nefarious in order to provide the team with their elite servants in their armies of darkness.