the story behind the titans in attack on titan
Attack on Titan It is later revealed that the Titans were created when Ymir Fritz found the "source of all organic life" and became the Founding Titan where she had the ability to create and control the Titans. When Ymir Fritz died as a side effect of having the Titan ability for 13 years, her soul was split into the 9 Titans where their abilities can be inherited by anyone once the previous wielder is dead. These Titans consist of the Founding Titan, the Attack Titan, the Colossus Titan, the Armored Titan, the Female Titan, the Beast Titan, the Jaw Titan, the Cart Titan, and the War Hammer Titan. The 145th King that wielded the Founding Titan's power fled to the island of Paradis where he used the countless Colossus Titans to make the walls and erased the memories of the Eldians he brought with him so that they didn't know anything about the outside world.