Nine Titans

"After her death, Ymir's soul was split into nine Titans, who build the empire of Eldia."

- Mr. Yeager recounts the origins of the Nine to Grisha

The Nine Titans (九つの巨人) are nine Titan powers that have been passed down through the Eldian race for nearly 2,000 years after Ymir Fritz's death. Each of them has a name, and are unique to the other Titans.

History
The Nine Titans have been passed down ever since they were split from Ymir Fritz's Founding Titan. As family relations play a significant role in passing inheriting memories from the previous inheritors of the Titans, the Nine Titans normally resided within noble families during the time of Eldia. Examples include the Fritz family with the Founding Titan and Tybur family with the War Hammer Titan. After the Great Titan War, Marley seized control over seven of the Nine Titans, and distributed them (except for the War Hammer Titan) among random Subjects of Ymir (now known as Warriors); the Attack Titan was lost and went into hiding. The Tybur family was allowed to keep their Titan because they were the first to fight for Marley, leaving them and the Reiss family (the Fritz family renamed) the only remaining Eldian houses left with their Titan after the war. The Reiss family later lost their Titan to Grisha Yeager in the year 845. After Grisha's Attack Titan ate Frieda Reiss' Founding Titan, the two Titans mixed into one. As a result, the number of Titans was reduced to eight.

Names and abilities

 * The Founding Titan (始祖の巨人) is able to turn Subjects of Ymir into Titans, manipulate the actions of Titans, and erase the memories of the Subjects of Ymir, but only while in the possession of (or in contact with) the royal family. It is connected to all the Subjects of Ymir via invisible "paths".
 * The Attack Titan (進撃の巨人) is said to always move ahead seeking and fighting for freedom.
 * The Colossus Titan (超大型巨人) is enormous and can evaporate its body to release immense amounts of steam.
 * The Armored Titan (鎧の巨人) is particularly good at hardening and is covered by hardened armor-like skin, except in key areas necessary for movement.
 * The Female Titan (女型の巨人) is able in every field and can attract nearby Pure Titans by screaming.
 * The Beast Titan (獣の巨人) has incredible throwing capabilities and stands a little taller than the others (aside from the Colossus Titan).
 * The Jaw Titan (顎の巨人) is small, fast, and agile; it is also equipped with strong teeth and claws capable of breaking almost anything.
 * The Cart Titan (車力の巨人) has great endurance and can stay transformed for long periods of time.
 * The War Hammer Titan (戦槌の巨人) can externally generate hardened Titan flesh and shape it into various structures.

Physiology
The height among the Nine Titans varies greatly, ranging from the 4 meters of Pieck's Cart Titan to the 60 meters of Bertolt's Colossus Titan. Many of them however range around 15 meters. Feminine Titan forms apparel to be slightly shorter than the masculine Titan forms, as Annie Leonhart's Female Titan is 14 meters and Frieda Reiss' Founding Titan was 13 meters.

Age does not affect the appearance of the Nine Titans. After acquiring the Attack and Founding Titans, Eren's Titan form becomes much more mature in appearance. The Warriors' Titan forms remains constant through their childhood and into early adulthood.

Some of the Titans have been shown to possess the ability to harden. The Armored Titan is particularly skilled at this, being able to naturally harden its entire body. It can also control the areas of hardening, removing armor for more mobility or creating claws on its fingertips. The Jaw Titan has naturally hard teeth and claws. The Female Titan is also capable of hardening. Annie's Titan is able to selectively harden regions of her Titan and even create a protective layer around her human body. The other Titans do not appear to have this as an innate ability, but it can be gained through specialized serums, such as the case with Eren's Attack Titan. Eren's Titan can harden its fists and areas around his body, which is used to seal Wall Maria. Zeke Yeager's Beast Titan can also harden, although it has not been shown.

Inheritance
The Nine Titans, and the power of the Titans, can be transferred to a new host, should they be devoured by a Titan. This allows an ordinary Titan to become a new human with the power of the Titans, and inherit one or more of the Nine Titan abilities as well as the memories of the previous inheritors. This has been the case with the Founding Titan for over a thousand years.

However, according to Rod Reiss, the power of the Titans resides within a human's spinal fluid, meaning that to gain the Titan's power, it is not necessary to eat the entire human, but rather a Titan can simply bite through the spine and ingest said fluid. Titan serums are, in fact, the spinal fluid of Titans, though study of the serums is difficult due to the serum's rapid rate of evaporation upon contact with air.

Inheritors of the Nine Titans do not adopt the appearance of the previous owners' Titans, as both Ymir and Frieda's Titans' appearances are vastly different from Marcel Galliard and Uri Reiss' Titans, respectively. Rod Reiss has claimed that humans can choose the serum that will give them a specific Titan form, meaning they are able to adopt the form given by the serum and not whatever form the Titan they eat possesses. However, the current inheritor's Titan form do experience certain changes depending on which of the Nine is received, as Ymir's Titan form gained sharp claws and teeth after acquiring the Jaw Titan and Armin's Titan form became much larger after acquiring the Colossus Titan. Eren's Pure Titan form was much smaller than his current form, and both Ymir's Titan form and Frieda's Titan form were noticeably more emaciated than their Titan bodies after inheriting their Titans.

If an individual with the Nine Titans dies before their Titan can be inherited by being devoured, that Titan will be passed on to the first baby among the Subjects of Ymir who is born directly after the said inheritor's death, regardless of distance or relation to the previous inheritor.

Trivia

 * Many transformed Titan forms are modeled after mixed martial artists. For instance, the Armored Titan is modeled after  and the Attack Titan is modeled after.
 * Grisha Yeager consuming the Founding Titan is the only known case where a person inherits one of the Nine Titans while already having one. In all other known cases, the receiver has always been a Pure Titan.