Ghouls are a race in Tokyo Ghoul franchise. These ghouls mainly eat human flesh while they cannot consume human food except coffee.
A ghoul in their basic Form will seem as ordinary as any other human. Though when a ghoul is pressured, excited or simply chooses to, their Eyes change with the Sclera becoming jet black and the Iris becomes a deep red. A ghoul in nature are predators. They are physically superior to Humans in nearly every way with their superhuman sense of Touch, Sight, Hearing, Smell, Durability & Strength. The only other sense which they do not excel in is there sense of taste, should they consume anything except humans the taste of what they eat or drink will become foul and or unbearable.
Other than their internal organs a ghouls body is incredibly resilient. They can withstand fatal injuries such as having steel girders fall on them, being stabbed by any common sharp object (such as a kitchen knife or blade) or falling from multiple stories without injury. In order to retain these abilities though a ghoul has to consume their primary source of food, that being Humans and with the exception of Coffee. Should a Ghoul be starved their bodies and traits will weaken so much to the point where they will be as vulnerable as a human. Eating Human food has a similar effect to them though not nearly as taxing. When a ghoul is at the brink of starvation they become animalistic in nature and will lose any ability to differ friend from foe. They will seek out a human to feed on even at the cost of there own life.
Every ghoul has one additional organ (Kagune) located at one of the 4 specific locations on their backs from the top down. Each Type has specific traits that separate it from one another. Every ghoul has a unique version on their own kagune types that set them apart from other ghouls of the same type making each rather unique. A Kagune itself is highly resilient and can only be penetrated by another Kagune. In addition, each type has an Advantage and Disadvantage to one anothers type in a Rock-Paper-Scissor like fashion and have drawbacks such as a strong offence but has a weak defence. A Ghoul Can bypass these flaws by training themselves and mastering there Kagunes.