Android Assassin

An Android Assassin is an android that can turn invisible, except for some anomalities in the air when it moved around. They had disintegrator blasters for assassinating their enemies.

At some point about 15 android assassins attacked the Doctor, however he used the energy from their blasters to charge a teleport device via his sonic screwdriver and teleport away in nano-seconds before he was disintegrated. (TV: The Witch's Familiar)