Titan (Anime)

Titans (巨人) are the primary antagonists and serve as the primary catalyst in the events of the Attack on Titan series. They are a race of giant humanoids that were thought to have first appeared 107 years ago and rapidly exterminated humanity to the point of near-extinction. In reality, the Titans are transformed humans from an unknown land outside the Walls that have roamed the earth for 107 years.

Appearance
Titans greatly resemble nude human beings. 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 have a masculine body shape, although all of them lack reproductive organs.

Titans, almost universally, have exceptionally wide mouths with an enormous number of small, square teeth. Although some only possess canines, a majority of Titans lack them. In all likelihood, they have and use incisors for their primary activity: eating humans. Titans do not possess a complete or functioning digestive tract, and merely have a stomach-like cavity that eventually fills up with what they swallow. After consuming a certain amount, they would be forced to regurgitate and empty out the cavity before they can eat more humans.

Behavior
Titans are compelled to seek out and devour humans for reasons currently 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 up its stomach-like organ with dead humans, it regurgitates them in a giant ball and continues eating more as soon as possible.

It should be noted, as mentioned above, that Titans eat humans for no other apparent purpose than killing them. They ignore all other animals and any non-human forms of life.

Most Titans have no intelligence at all and are simply mindless beasts, easy to trick, distract, or deceive. However, some Titans, mostly Titan shifters, possess a vast level of intelligence comparable to or exceeding an experienced and cunning human. For example, the Female Titan and, to a lesser extent, the Colossal Titan display acute intelligence, a trait not found in an ordinary Titan. A Titan encountered by Ilse Langnar possessed enough intelligence to speak and bow before her, calling her "Lady Ymir".

However, although most Titans show no visible or audible form of communication, they are apparently aware of - and able to deduce hostile intent from - other Titans and Titan shifters, as demonstrated when Eren Yeager first transformed into his Titan form and was attacked almost immediately by other Titans who perceived him as a threat. Titans do possess the ability to roar, but do not appear to possess the vocal organs necessary to speak human languages.

The most dangerous aspect of the Titans is their unpredictability. They do not follow a strict set of guidelines and have seemed to increase in abilities and attributes as the series goes on. After the supposed breach of Wall Rose, Titans were seen moving in the dead of night when they should be inactive, traits they normally do not express.

Creation
Titans are human in nature. It is unknown how the very first Titans came to be. People are able to turn into Titans after being injected with Titan spinal fluid, triggering a transformation from human form into Titan form. The time between the injection and transformation is very brief, though not instantaneous. Titans oftentimes bear strong resemblance to their original human bodies, though women who are turned into Titans lose any feminine body features. Ymir is currently the only character aware of how Titans are created as she herself was transformed into a Titan by unnamed soldiers.

Physiology
The Titans' body structure and power source are very mysterious and they apparently violate several known laws of science, seemingly capable of spontaneously generating both energy and mass. 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 possess vocal organs and are able to emit simple sounds like roars and screams, yet they apparently do not need to breathe. 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. Individual Titans seem to possess varying levels of stamina once deprived of sunlight; the captured Titan 'Sawney' became docile and nearly comatose after only an hour's deprivation, while fellow captive 'Beane' maintained a high level of activity three hours after last seeing sunlight.

Titans' bodies also seem unusually light for such large creatures - a severed arm is described as weighing almost nothing, and they are able to move at high speeds despite their size. Due to their size, Titans possess enormous strength and when combined with this lightness, they can put on amazing bursts of speed and agility.

In addition to their size, speed, strength and large numbers, Titans also possess incredible regenerative abilities - the only sure-fire way to kill them (known to date) 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 (although, there are rare instances where the head will not regenerate if the nape is cut through or blown off). It should be noted that the vulnerable area is where the real human body would be for shape-shifting Titans, as proven by Eren Jaeger. When struck at this site, the human controlling the Titan (or rather, what remains of them) is decapitated, killing both. After death, Titan corpses rapidly evaporate to skeletal remains, then to nothing at all.

How Titans react to pain stimuli varies from one to another. Many Titans will utterly ignore injuries which would be agonizingly painful to a human, such as losing limbs, being impaled through the heart, or having their eyes gouged out (even if such injuries will soon regenerate). In combat, some Titans will completely ignore armed humans who are attacking them, and simply proceed to attempt to eat whichever human is closest to them. Others seem vaguely aware of humans who are attacking them, and if injured will have a reaction that might be pain but more accurately seems like simple annoyance. Some actually do seem to react in pain and shout when they are injured. In Hange's experiments, Bean shrieked in pain when they gouged out its eyes with a heated metal spear, but Sonny seemed oblivious to the fact that Hange had impaled it through the heart region using a spear.

Types of Titans
Titans are classified according to their size and abilities. The following is a list of various known Titans so far in the series.

Trivia

 * Some Titans are modeled after friends and acquaintances of Hajime Isayama. Sometimes, he will even take requests.
 * In the August 2016 Issue of Bessatsu Shonen Magazine, Isayama was asked of what is it like to come out of a Titan's body. He stated, "Just think that it’s like coming out from a sauna."
 * While many Titans has a masculine appearance, some Titans seen (not including Titan shifters) have had feminine facial features (though they still have a masculine body shape).