Much like the Romero Zombies of modern day horror fiction, Titans are hinted to be an off-shot of the human race now cursed to forever devour the rest of humanity.
Physical Appearance and Charcateristics
Titans are creatures closely resembling human beings, but with various deformities, ranging from either over/under-sized heads and limbs, massively fat stomachs, or even skeletal frames. As the species' name would imply, titans dwarf over any human being. All titans keep their eyes constatly opened, their mouths posses lots of molar teeth used to grind human flesh. Titans possess no visible reproductive organs, thus it is unknown how they keep increasing their numbers. Each titan possesses unique facial features and hair style, much like any individual person.
Do to their varying sizes, ranging from only three meters, to up to gargantuan statures, titans have been categorized based on how tall they are.
Behaviour and Goals
Despite their enormous strength and toughness, Titans' bodies are unnaturally light for their size. The Titans appear to have no objectives other than killing and consuming humans, which they do only by instinct, as they do not seem interested in attacking other animals. They survive on sunlight and do not need to eat to survive - they actually lack any digestive organs, forcing them to occasionally regurgitate consumed prey. Dead Titans' corpses decay at an extremely fast pace. They have hard skin and regenerative abilities, and can only be killed by causing a deep incision on the back of the neck. This weakness led to the development of the Three Dimensional Maneuver Gear, allowing humans to navigate quickly in a three dimensional space to access the Titans' weak point. The creatures are at numerous points mentioned to have exceptionally high body temperature. As a result, their bodies emit steam when regenerating, decaying or under heavy exertion; the 60-meter Titan's body emits steam constantly. Some humans such as Eren Jaeger, have the unique ability to summon and control a Titan body. While in this form, the human's normal body rests in the weak point at the base of the neck, connected via masses of muscular tissue, indicating a connection between the sentient and feral Titans. Certain Titans are noted to be Deviant-Type (奇行種 Kikō-Shū), acting in a way that is not normal for Titans, such as not eating humans directly but acting in a way to help their fellow Titans.