The Quarks
The Quarks were the deadly (cough) robots used by The Dominators, a race of evil beings who liked to um, dominate, wear fancy outfits with giant shoulder pads and harass planets full of hippies.
The Quarks were devised by Mervyn Haisman and Henry Lincoln who had previously successfully created the Yeti as an iconic Doctor Who monster the year before. Unfortunately a walking giant rug that's roar is the sound of a slowed down flushing toilet isn't really marketable in the toy world unless you're George Lucas. So they created the Quarks for the story The Dominators in August 1968.
The Quarks problem was they were just not threatening, sure they had guns but because of their little legs you could probably outrun them by breaking into a gentle stroll. They also made extremely non threatening high pitched bleeping noises. In fact you can pretty much sum up the Quarks as being a toddler.
Whenever they were dispatched by The Dominators to do anything, they would just tend to wander around aimlessly occasionally firing at things and then run out of power after about 10 minutes, just like a toddler who's give you the runaround for a while and then fall asleep.
In fact this episode was so bad that the production team cut the number of episodes from 6 to 5 and wrote the ending themselves, which annoyed Haisman and Lincoln who asked for their name to be taken off the script. They were also pretty annoyed when they found out the BBC were going to bring out a load of Quark toys & merchandise without their knowledge. Needless to say the general public couldn't care less about the Quarks, the BBC never made a penny in merchandise sales, Haisman and Lincoln refused to work for Doctor Who ever again and so the Quarks were consigned to the dustbin of history.
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The Security Robot
Terry Nation is back, and this time he has his own series. After trying to flog the Daleks to the Americans & Hollywood (And failing) Terry Nation comes back to the BBC, writes a few Doctor Who scripts (Genesis Of The Daleks being the standout), then writes the hit series 'Survivors' about a plague wiping out most of the human life on Earth. Because of the success of these he is allowed to start his pet project. A TV show based on the movie the Dirty Dozen only set in space where a band of various criminals would battle against the corrupt Earth federation. It's name ... Blakes 7.
What Nation decided was that for this series to get the attention it warranted it needed something as big as the Daleks to make the series take off. With Blakes 7 being about criminals against a corrupt government it made race of robotic aliens that would destroy everything in it's path rather unworkable so he came up with the Security Robot.
The Security Robot would just hang around a few military bases defending them from intruders. It had a really powerful flamethrower, not like a short burst of flame but a real life flamethrower although not as powerful.The biggest problem with them was they made so much noise, you could probably hear one whirring towards you 10 minutes before it actually arrived meaning by the time it got there everybody had either hidden or legged it.
They appeared in a couple of early episodes of the series run but they were slow, cumbersome and a bit silly. When it was decided that having a couple of actors play guards it made the scenes so much easier to shoot and they were dropped for good.
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The Cybermen
It took them a while to get it right but finally someone succeeded.