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|If you ever interfere with us, the millions upon millions of Titans in the Walls will flatten the entire world.|
|— Karl Fritz's threat to other nations|
The Wall Titans (壁の巨人 Kabe no Kyojin?) are Abnormal Titans similar in appearance to the Colossal Titan, one of the Nine Titans. They possess the ability of hardening and exist in the order of the millions within the three Walls.
In the year 743, King Karl Fritz used the power of the Founding Titan to create and command tens of millions of these Titans to create the three Walls and protect the last Eldian territory on Paradis Island. The lack of sunlight inside the Walls has rendered them immobile ever since, although King Fritz threatened to release them and use them to flatten the Earth should Paradis Island come under attack.
The Wall Titans are similar in appearance to the Colossal Titan in that both their surfaces are covered primarily in muscle tissue and lack skin (although the Colossal has exposed bone over the muscle tissue of its form). They have proportionally small eyes and lip-less mouths which exposes their teeth. Their exact height is unknown, but seeing as they make up the Walls and are implied to stand partially underground, they may stand as tall as the Colossal Titan.
Each of the Wall Titans has the ability to harden not only the top layer of their skin, but much of their body, leaving them deprived of skin and hair. Using this method, they linked together to create the Walls as a collective mass of hardened Titan skin. Serving as both protection for Eldians and secrecy for the king, as the Titans were made to appear invisible.
In the year 743, after King Karl Fritz abandoned the conflicts of Eldia causing the Great Titan War, he fled overseas with most of the Fritz royal family and remnants of the Eldian populace to Paradis Island, Eldia's last remaining undisputed territory. He used the power of the Founding Titan to create and order tens of millions of Colossal Titans form the three concentric Walls to protect the Eldians. The King sent a message to the people of Marley, demanding that the Eldians on Paradis Island must be left alone or else the Colossal Titans inside the Walls would "flatten the entire world."
During the battle between Eren Jaeger and Annie Leonhart's Titans in Stohess District, Annie attempts to escape by climbing the Wall but is stopped by Mikasa Ackermann. However, it damages part of the Wall, and after the battle a huge chunk is torn off, revealing the face of a mysterious Titan.
The missing chunk of the Wall is later noticed by some Scouts. The Titan within the Wall follows the Scouts' gaze. Pastor Nick then catches up with Hange Zoë and calls for the immediate covering up of the Titan, as the sunlight eventually will enable its movement. After Nick ignores Hange Zoë's questions about it, he is nearly thrown off the Wall by Hange, but still refuses to reveal any details he might know because of the Order of the Walls' forbidden nature to disclose secrets.
During the expedition to Shiganshina District, while thinking about where Reiner Braun and Bertholdt Hoover might be hiding, Armin Arlelt remembers the Wall Titan found inside Wall Sina, which makes him deduce that the Warriors may be hiding in a cavity in the Wall, as this provides a high spot from where they can watch the Scouts' movements while staying out of sight. This is proven to be true after Reiner Braun is found hiding this way.
During the festival hosted by the Tybur family, Willy Tybur tells the world of the truth about the Walls, the Great Titan War, and King Karl Fritz. He reveals that due to the King's vow of pacifism which prevents the Founding Titan from being used for war, the Wall Titans were never a true threat. However, due to a coup d'état in recent years, the military of Paradis Island have overthrown the previous royal government and rendered the King's ideology of peace ineffective. Now that the Founding Titan belongs to Eren Jaeger, who is seemingly capable of using its powers despite not having royal blood, and without interference from King Fritz's will, the world is truly in danger of the Wall Titans for the first time. Eren himself admits this to be true.
As the Royal Government discusses Zeke Jaeger's requests which were brought to them by the Anti-Marleyan Volunteers, Eren Jaeger reveals he is able to activate the powers of the Founding Titan by coming into contact with a royal-blooded Titan. He also states that this method can be used to awaken the Titans within the Walls without invoking the vow of renouncing war.
After Kiyomi Azumabito arrives on Paradis Island, she divulges the rest of Zeke's strategy to save Eldia which involves unleashing some of the Titans inside the Walls to demonstrate its destructive power. The island would then need to keep that power in reserve for the next 50 years as Eldia advances technologically.
- In the second compilation film, the Wall Titan's design is slightly altered to make it look more like its manga counterpart.
- This change stays in Season 2 of the Attack on Titan anime.