Transformer
The Transformers are a species of robots (mostly) originating from the planet Cybertron.
The name stems from their ability to "transform," to change from a robotic primary mode (usually, but not always, humanoid) into an alternate form, generally vehicles, weapons, machinery, or animals. (In some continuities this abillity to transform is innate to all members of the species, in others it was a wartime innovation that was adopted by most, but not all, Cybertronians.)
Biology
Transformers are living beings, despite their mechanical bodies. Many continuities portray this life as being granted by a soul-like spark.
They are generally *very* large in comparison to Earth lifeforms, (two or three times the height of a human seems to be about average), though Transformer's size can vary in the extreme. Their have been some (see Browning) small enough to fit in a human's palm and others a good deel larger than a mountain.
Unlike humans who need air and water as well as fuel, the Transformer's only major biological need to assure their continued functioning is fuel. Energon is the most common and prefered form of Transformer fuel, but other alternitives may be substituted if it is unavailable.
For more information on Transformer biology see:
Culture
The most distinctive facet of Transformers society has been it's near continous state of war.
Toys
The Transformers were introduced by Hasbro in 1984 with the toyline know known as Generation 1 and have gone through numerous incarnations since, with the latest being Classics.
