Smiler

The Smilers were a type of Androids that were aboard the Starship UK.

Profile
The Smilers were mounted in booths around the Starship UK. At any time a citizen broke the law or was deemed unnecessary, the Smilers would take action. The Smilers rotated their heads to show three faces: happy, angry (for warnings), and malevolent (when attacking). While they had three faces, they appeared to rotate their heads 180 degrees (which should mean they'd only have two). This might mean that faces can be removed when they rotate. While they initially appeared to be merely heads, in extreme circumstances they could be made to leave the booths and attack. They could also quickly repair themselves when damaged. The terrified population kept their booths clean and never dared get too close to them. There seems to be no logic how one minute there is one head at the back of the original head, and when it rotates twice, a completely different face takes over the back of the Smiler's head. (DW: The Beast Below)

Behind the Scenes
The Smilers are going to appear at Doctor Who Live.