Titans, or Kyojin, are giant humanoids who act as the catalysts and the antagonists in Attack on Titan series. At the start of the events portrayed in the series, TItans are shown to exist outside the walls of the city where the last of the humans are surviving. Whatever information we have about the Titans at the beginning of Shingeki no Kyojin is whatever the Survey Corps had been able to collect during their many costly expeditions outside the walls.

The Titans consumed humans and their only motive seemed to be getting inside the walls so that they could devour the rest of humanity. They could only operate in sunlight and they showed no interest in devouring any other living beings or animals. They did not need food or drinks to survive.

People who lived inside the walls believed that the man-eating Kyojins first appeared around 107 years back and they drove humanity to extinction.

The three great walls were the only things that kept the Titans from entering the last settlement of humans and completely eradicating them. However as the series progresses, we get more and more information about the Titans and who they really are. Read on to find out the rest. 

Who are the Titans in Attack on Titan?

The following part consists spoilers for all Seasons of Attack on Titan, If you haven’t seen the series and don’t want to spoil the experience we suggest you stop right here.

As the first season progresses we find out that Eren Jaeger has the ability to turn into a Titan, suggesting that the other Titans out there had to have some connection to human beings. After all their appearance, with limbs and features, greatly represented nude human beings. 

Towards the end of the first season and over the course of the second season, we understand that Eren is not the only one who is capable of transforming into a Titan at will and there were other humans who were able to do it (at least five including Annie, Bertholdt, Reiner, Ymir and the Beast Titan). Their motives or where they came from were not clear yet.

The major reveal comes in the third season ,when the Survey Corps with Eren Jaeger, manage to recover the three books that were locked away by Grisha Jaeger in his basement, containing the secret about the titans.

Titans are artificially transformed humans!

By the end of Season 3 we realise that Titans are humans who have been artificially transformed against their wishes by the people of Marley and left to roam free in Paradis Island. 

According to the books recovered from basement of Eren’s home in the now destroyed Shiganshina district, there are humans who live outside the walls too. Marley is a nation which exists beyond the wall across the ocean from Paradis Island. 

Only people of a particular race could transform into the titans. They are the Subjects of Ymir, or the Eldians. The Eldians had used to power of Titans to conquer the other nations including Marley and build their empire. However when their empire fell after the Great Titan War, most of the Eldians followed their king Karl Fritz and settled in Paradis Island across the ocean guarded by the walls.

However, some Eldians had stayed back in the enemy territory. They were conquered by Marley and treated as inferiors to the citizens of Marley. If the Eldians were accused of acting against the Marley empire, they were converted into pure Titans and left in Paradis Island to roam for eternity. These pure titans have slow and clumsy and are shown to be mindless.

It is these forcefully converted Eldians that we see as pure Titans, or the titans that cannot transform back to humans, from the beginning of Attack on Titan.

How are Eldians converted into Titans?

Subjects of Ymir, or the people of Eldian race were able to be converted into Titans by injecting the spinal fluid of a Titan into them. The injection of the fluid caused instantaneous transformation in them. The titans thus formed bore strong resemblance to their original human form.

Marley, who exploited this technique, used it to forcefully convert the Eldians into Titans and used them in battles to conquer other nations. The ones who disobeyed or acted against the Marley empire were the ones who were punished and left to roam for eternity as pure Titans on Paradis Island, which was referred to as Heaven in Marley.

Who are the Intelligent Titans?

The intelligent titans too are Eldians. However they have been drafted by the Marley military to act the bearers of the powers of the Nine Titans. Annie Leonhart, Bertholdt Hoover and Reiner Braun were Eldians living in Marley and drafted into their military so that they can be used as weapons against the opponents. 

They are able to transform into titans by inflicting an injury on themselves.

In the series they were tasked with finding and capturing the Founding titan, whose power Marley wanted so that they could better control the pure Titans and also completely obliterate the Eldians living on Paradis Island.