Auton

The Autons were metamorphic android robots, artificial life forms that were essentially life sized plastic dummies, animated by the Nestene Consciousness. Though they are not the only creations of the Nestene Consciousness, they were the most common and the most easily identifiable.

(The Autons that were fashioned after the Roman Soldiers from Amy's childhood most likely were not made out of plastic.)

Appearance and abilities
The typical Auton did not look particularly realistic, resembling a mannequin, being robotic in its movements and mute, although an Auton leader could speak in a robotic voice. (DW: Terror of the Autons) Despite their solid appearance, Autons could change the shape of their features and limbs. (DW: Rose). Autons concealed deadly weapons within their hands, which could kill or vapourize their targets using psychic projections. They were also excellent trackers, as they could follow other creatures by their brain-wave patterns. (PDA: Synthespians™)

More sophisticated Autons could be created, which looked and acted Human except for a slight sheen to the skin and a flat sounding voice. Autons could also copy specific individuals, though these copies were imperfect. When duplicated, the originals were kept alive to maintain the copy. A copy of Channing was maintained by the Nestenes' affair during their first attempted invasion of Earth. (DW: Spearhead from Space). Mickey Smith was also copied by the Nestene to act as an information gather on the affairs of the Doctor. (DW: Rose).

Later models could mimic humans perfectly, and could also be used as sleeper agents. These Autons would be implanted with false memories and actually believed they were the subjects they duplicated. The Nestene Consciousness could then at any time asserts its influence over them again, but the duplicate Auton could resist should it have developed the necessary willpower. (DW: The Pandorica Opens)

History
During the first attack on the Earth by the Nestene Consciousness, the invasion was co-ordinated by a Swarm Leader known as Channing. Taking over a plastics factory, Channing arranged for standard Autons to be mass-manufactured and placed in shops across Britain. Channing also obtained a contract from Madame Tussaud's to make plastic "waxworks" of key members of government and the military. The attack was co-ordinated first thing in the morning, when the Autons broke out of shops to attack key strategic positions whilst the facsimiles helped soften resistance. Unfortunately for the Autons, the the Doctor and the United Nations Intelligence Taskforce had detected their base and rigged a device capable of destroying both Autons and the Nestene. (DW: Spearhead from Space)

Some months later, the Nestene made an alliance with the Master. Although the Nestene did use standard Autons for this operation, the assault relied on deadly plastic daffodils, but was again foiled by the Third Doctor and UNIT. (DW: Terror of the Autons)

After the Nestene's protein planets were destroyed during the Last Great Time War, it arrived in 21st century London and used standard Autons to conquer the planet. When the Doctor came to investigate, it sent Autons to try to stop him. When Rose Tyler got in the way, it also sent an Auton impersonator of her boyfriend Mickey Smith to try to find out more. The Doctor was able to use the Auton's head to track down and confront the Nestene Consciousness. When the Nestene realized it was in danger, it activated the Autons to cause them to go on a rampage. When the Nestene was killed with anti-plastic, the Autons were deactivated. (DW: Rose, Love & Monsters)

The Nestene also used Autons when they attempted to take over the New Earth Republic in the 101st century. They used both standard and facsimile versions. (PDA: Synthespians™)

When the Nestene Consiousness joined the Alliance, they produced Autons disguised as Roman soldiers in 102 AD. These, believing themselves to be genuine Roman soldiers, tricked the Doctor, who realised too late what they were, and imprisoned him in the Pandorica. One, fashioned after the late Rory Williams, actually attempted to resist the call to arms, not wanting to fire upon Amy Pond. Afterwards, the Auton helped the Doctor resuurect Amy with the Pandorica and save the universe. After the Doctor reset the universe and time, this Auton and all of the Roman soldier ones were erased from existance as the cracks never happened and thus the Alliance was never formed. (DW:The Pandorica Opens/The Big Bang).

River Song once dated an auton with a removable/replaceable head.(DW: The Big Bang)