Doctor Who: EVERY NuWho Villain And Monster Ranked Worst To Best

Appears in: A Town Called Mercy.

The Gunslinger, aka Kahler-Tek, was one of the individuals Kahler-Jex experimented on. The prequel mini episode The Making of Gunslinger shows Tek volunteering on the assumption that he would be deployed on "peacekeeping missions on off-world colonies". His transformation echoes the horrifying full Cyber-conversion with the whirring saws and Darth Vader's painful operation after his duel with Obi-Wan on Mustafar.

The realisation of the monster he had become dawned on him, so Tek began hunting down the scientists who created him. It eventually led him to Jex and although Tek was denied personal revenge on his fellow Kahler, he found a renewed purpose in becoming Mercy's protector.