10 Doctor Who Side Characters With Tragic Backstories

The Terminator-esque Gunslinger is positioned as the villain of Series 7's A Town Called Mercy, and he certainly does cause a few headaches for the Doctor throughout the course of the episode. But at heart, he is not a bad person.

The Gunslinger's real name is Kahler-Tek, and once upon a time, he was an ordinary soldier, serving in a military academy on his home world, Kahler. Soon after, war broke out - a devastating affair that stretched on for almost a decade, utterly destroying half of the planet in the process.

At this point, Kahler-Tek was told that he had been selected for a special peace-keeping mission on an off-world colony, but in actual fact, he was about to become a guinea pig in a twisted experiment concocted by a scientist, Kahler-Jex.

Desperate to end the war, Kahler-Jex mutilated ordinary soldiers and literally fused their flesh with weapons, all in an attempt to create unstoppable cyborgs. These soldiers had their memories and past lives erased, transforming them into merciless killing machines that served without question.

According to Kahler-Jex, his army of robotic creations were so powerful that they ended the war within a week. But the innocent lives that had to be sacrificed to get there - including Kahler-Tek's - weighed heavily on his conscience.