M is for... Monoids

Millions of years in the future, the Monoids sought refuge on Earth after their own planet suffered some terrible catastrophe. Reptilian in nature, they had a single eye beneath a thick mop of hair. Mute, they learned to communicate with humans via a form of sign language. 

When the Earth itself came under threat, the entire population - human and Monoid - embarked on a 700 year-long voyage to a new home on the Earth-like planet Refusis II. The majority were miniaturised and placed in suspended animation, but a certain number of humans were to act as Guardians, accompanied by a similar number of Monoids. They were used as servitors by the Guardians.

When the TARDIS materialised on the vast spacecraft - nicknamed 'the Ark' by the Doctor's companion Dodo - they noted how the Monoids were treated as a servant class.

Unfortunately Dodo was suffering from the common cold, and this ran riot through the Guardians and Monoids who lacked a natural defence to the virus, it having been eliminated generations ago. It proved fatal in this environment. The Doctor found a cure and the TARDIS departed - only to immediately arrive back on the Ark at a point 700 years later, when it was approaching Refusis II.

The Doctor and his companions discovered that the Monoids had taken over in the intervening centuries. They had grown stronger thanks to some after-effect of the cold virus, which had in turn weakened the Guardians. The Monoids had developed artificial voice boxes, and had also created heat-guns.

A revolution had taken place and the Guardians were now a slave class.

The Monoids adopted a numerical system to identify themselves, with their leader being "One".

Monoid One proposed to seize Refusis II for his people alone. Their miniaturised brethren would be transferred down to the planet, but the humans would be forced to remain on the Ark, which would then be destroyed by a powerful bomb.

There were some amongst his people who disagreed with Monoid One's autocratic rule, however, thinking he was leading them into danger. Civil conflict broke out between One's supporters and those of Monoid Four - his chief critic. The bomb was found and detonated harmlessly in space, thanks to one of the powerful incorporeal Refusians. Monoid Four's people were the victors in their internecine struggle, but many had been been killed on both sides.

Human and Monoid would have to learn to cohabit peacefully on Refusis II.

Played by: Edmund Coulter (One), Ralph Carrigan (Two), Frank George (Three), John Caesar (Four). Voiced by: Roy Skelton, John Halstead. Appearances: The Ark (1966).

• The Beatles-like mop of hair was added to disguise the end of the zip which ran up the back of the costume. An early close-up shows how the eye is really half a ping-pong ball held in the actor's mouth by a small peg, which allowed him to manipulate it.
• John Caesar appeared as a background artist in a number of stories, ranging from The Romans to Invasion of the Dinosaurs.
• This is the first story to feature Roy Skelton, who would go on to take over from Peter Hawkins and David Graham as the voice of the Daleks for much of the classic era of the series.
• A puppet Monoid features in The Time of the Doctor.
• A deleted scene from An Adventure in Space and Time would have seen someone dressed as a Monoid attending Verity Lambert's leaving party - despite the fact that they weren't created for another year after that event.