Cyberman (The Pandorica Opens)

This Cyberman was left behind in 102 AD to guard the Pandorica only for it to become heavily damaged, the Eleventh Doctor later suspecting that it had run afoul of the locals. Left inactive for so long, its organic components eventually decayed.

When the Doctor and Amy Pond arrived, the Cyberman's severed cyber-helmet followed them down the stairs, seeking to upgrade Amy. Before it arrived, it commanded its severed left cyber-arm to attack them, it being used to deliver an incapacitating electric shock to the Doctor.

After ejecting its decayed organic skull, the cyber-head fired a numbing dart at Amy before summoning the rest of its body. Though it managed to corner her into a side chamber, it was ultimately deactivated when Rory Williams, revived as an Auton, impaled it his sword. When the Doctor recovered, he found the Cyberman's weapon cache and briefly suspected that its presence meant that the Pandorica held a Cyber-being within but ultimately dismissed the idea. (TV: The Pandorica Opens)