Xentronians

Xentronians are a race of aliens that appeared in the nineteenth Give Yourself Goosebumps book, Escape from Camp Run-For-Your-Life.

History
Xentronians run Camp Running Leaf to capture children and brainwash them so they can send them to their home planet of Xentron to be slaves in the mines.

Physical appearance
The Xentronians are humanoid aliens that have tinted blue skin, golden eyes, no nose, and a small round hole on the top of their heads.