OK, I'm slipping behind already, but I'll try and catch up with some more species found in the wide worlds of science fiction. This week's article could be technically be noted as not an alien since the species in question are of course machanical in nature, but since they are alive, intelligent and independent I think I'll let them get away with it, oh and they are also undeniably cool!
Average Height: Varies on an individual basis
I can't claim to be a long time Transformers fan and readily confess that my enthusiasm for this species comes almost solely from the new film. The notion of a living species with mechanical components instead of organs is a fascinating one and gave the film a strength that carried over from the former cartoon series and popular toy. The transformers have a diverse and wildly varying continuity which I'm going to mostly skirt around, though I will try and avoid making direct claims based on the film as they may differ from older continuity and inevtiably annoy someone.
The Transformers are a living mechanoid species from the planet Cybertron. How they came to be is a mystery even to the species themselves as it is long shrouded in their past. Some believe they were formed from a natural interworking of cogs and levers, eventually developing into full mechanoids. Others believe that they were created by God like beings to serve in their battles, still other that the life giving Allspark provided them with life. However it happened the Transformers are most definitely alive.
They are gifted with the most incredible abilities. They processors can handle information at incredible rates and their weapons far surpass the most advanced of Earth's technology. Their most amazing ability is to change shape to attack or disguise themselves. All they need is an image of a construct (say a car) vaguely similar to themselves and instantly transform into an exact replica of it, perfectly disguised. When not in this they reside in "protoforms" often vaguely humanoid, but still clearly mechanical and clearly alien.
The history of Cybertron and it's inhabitants is a long and tortured one with multiple accounts and histories branching far and wide. But the central core of their lives for many millenia has been the two factions of the Autobots, led by the benevolent Optimus Prime and the Decepticons, led by the power hungry Megatron. This war has ravaged their world, flung them accross space and eventually lead them to Earth where they have often carried out their war hidden among the humans, this war has defined Transformers for a long time and will for years to come.