Colossals

Colossals greatly resemble human beings in that they are bipedal creatures with the same number and arrangement of limbs and features one would expect in human beings. They are all deformed by human standards to a greater or lesser degree, ranging from minor abnormalities in proportions (enlarged head, small limbs etc,) to apparently lacking skin and subcutaneous tissues, although they do not bleed from such deformities, indicating that they perhaps possess some other mechanism to compensate for this. The vast majority of Titans are masculine, although all Colossals lack sex organs- their method of reproduction is currently unknown.

Colossals almost universally possess widened mouths with an enormous number of small, square teeth. They apparently lack canines, although possibly not incisors, and use these in their primary activity-eating humans. Colossals are compelled to seek out and devour humans for reasons unknown, as they do not derive any real sustenance from them-they did not taste human flesh for nearly a century after the walls went up, but this did not affect their activity or numbers. It should also be noted that once a Titan has filled what passes for its stomach with dead humans, it regurgitates them and continues eating more as soon as possible.

In addition to their size, speed, strength and large numbers, Colossals also possess incredible regenerative abilities-the only sure way to kill them is by slicing out the nape of the back of the neck. They regenerate lost and damaged body parts within seconds to minutes, including severed heads. After death, Colossal corpses rapidly evaporate to skeletal remains, then nothing at all.

Colossals' body structure and power source are very mysterious and apparently violate several known laws of science. Their extremely high level of activity and body temperature indicates the need for a massive intake of energy to fuel them, yet they apparently never need to eat at all. They do seem to become less active at night or if deprived of sunlight, and so it may be possible they draw their primary source of energy from the sun.