Green with one eyes
They first appeared in Cat Got Your Brain? (Series 2 Episode 18) so they could study Shaun and Pidsley. One of them spilled coffee on the control panel, and the other one pushed buttons frantically, so no changes could be made. Unfortunately, this caused the machine to malfunction, switching their brains, then the spaceship tilting left and right, moving back and forth, dropping Shaun with Pidsley's brain in the Farmer's house, then dropping Pidsley with Shaun's brain in the barn.