Beast Titan

"Levi may be humanity's strongest soldier... but he's no match for our strongest warrior."

- Reiner Braun's faith in the Beast Titan

The Kemono no Kyojin (獣の巨人) is one of the Nine Titans that possesses the ability to guide and direct mindless Titans and can create new Titans from common Eldians. It is currently in the possession of Zeke Yeager, though it will soon be passed on to warrior cadet Colt Grice.

Abilities
While the exact inherent abilities of the Beast Titan are unknown, Zeke Yeager's Beast Titan gained significant unique abilities. Thanks to the royal blood within him, this is possible through the administration of Zeke's spinal fluid to Eldian victims. Despite the various flaws in the abilities of Zeke's Beast Titan, they have proven to be invaluable to Marley's needs and are unprecedented in the history of the Beast Titan, comparable in nature to the powers of the Founding Titan itself.

Titan creation
One of the most perilous attributes of Zeke's Beast Titan is the ability to turn human Eldias into Titans without the use of Titan serums. This is accomplished through a scream-based trigger, much like the abilities of the Founding Titan and the Female Titan. This ability can be used to devastating effect on the unsuspecting, such as the initiation of the Wall Rose invasion after the residents of Ragako were turned into Titans with the Beast Titan's power, and when the Marley military made use of this power to drop Titans onto Fort Slava in an airstrike. However, this is only possible when the victim has by some means come into contact with Zeke's spinal fluid. Therefore, this power is severely limited in battle, such as when Zeke was unable to turn any members of the Survey Corps into Titans during the Wall Rose invasion and the battle of Shiganshina District.

Titan control
Zeke's Beast Titan is able to exercise some control over mindless Titans through a scream-based ability. Through vocal commands, the Beast Titan is able to direct the actions of mindless Titans and can command them to refrain from eating humans and stay in place if necessary. Titans under Zeke's control are even able to function using only moonlight without falling into fatigue. However, this ability is evidently imperfect in comparison to the Founding Titan. Titans under the control of the Beast Titan either seem to be capable of ignoring orders or occasionally do not receive or comprehend orders given. Furthermore, Titans under the Beast Titan's control cannot act upon the unspoken will of the Beast's user, unlike the Founding Titan, and must be given some sort of direct verbal signal before taking action.

History
The Beast Titan, like all the Nine Titans, was brought into the world after the death of Ymir Fritz. In the 1,700 years following her death, the Beast Titan was held in the possession of one or several of the warring Eldian houses subservient to the Founding Titan. After these seventeen centuries when the 145th King of the Fritz family abandoned the conflicts of Eldia and relocated to Paradis, the Beast Titan was taken by the nation of Marley during the Great Titan War.

At some point before the year 845, Zeke Yeager was chosen to inherit the power of the Beast Titan. Additionally, he was granted the title of warchief over all the warriors of Marley.

Clash of the Titans arc
In the year 850, Zeke Yeager infiltrates Wall Rose and uses the power of his Beast Titan to transform the residents of Ragako into Titans, possibly as a way to test the strength of the Eldians within the Walls. Shortly afterwards, a small group of his Titans is spotted by Squad Leader Mike Zacharius, who begins a mission with fellow soldiers and recruits of the Survey Corps in spreading the news of a Wall Rose invasion. After killing five of Zeke's Ragako Titans, Zeke takes Mike's horse and throws it his way, sending him falling into the mouth of a gluttonous Titan. Zeke's Beast Titan stops the remaining Titans from attacking while he asks Mike about the weapon the Eldians are using against the Titans, but Mike is too afraid to speak. With no useful responses, the Beast Titan takes Mike's maneuvering equipment and leaves the scene, releasing his hold over the Titans and allowing for them to eat Mike alive.

Later that night, the Beast Titan climbs Wall Rose, tearing pieces of the Wall off to use as projectiles against a team of Survey Corps soldiers resting at Utgard Castle. He then leaves Wall Rose, not to be seen again for some time.

The Uprising arc
Presumably two months following Zeke's invasion of Wall Rose, Zeke meets with his warrior subordinates Reiner Braun and Bertolt Hoover in the ruins of Shiganshina District. The two want to return into the Walls to rescue their comrade Annie Leonhart, though Zeke believes their best course of action is to wait for the Survey Corps to arrive in Shiganshina in order for the warriors to obtain the sought-after "Coordinate". Conflict arises between Zeke and the two warriors, who then decide their course of action through combat between Zeke's Beast Titan and Reiner's Armored Titan. The Beast Titan brutally overpowers the Armored Titan, and the decision is made to remain in Shiganshina.

Return to Shiganshina arc
When the Survey Corps arrive in Shiganshina District as Zeke had predicted, the Beast Titan acts as the commander of the Titan forces throughout the battle. As the majority of the Survey Corps is within the district, Zeke uses the power of his Titan to summon a blockade of Titans to the north of the district, preventing any escape. At this time, Zeke also collapses the northern breach of the city, cutting off the troops from their horses north of Wall Maria. Afterwards, Zeke commands the smaller Titans under his influence to attack the soldiers north of the Wall. The Survey Corps battle with the smaller Titans for a short time, and upon hearing the warning call from Reiner's Armored Titan within the district, Zeke's Beast Titan hurls Bertolt Hoover into the city in a barrel that had been waiting on standby atop fellow warrior Pieck's Titan, the Cartman. After a brief delay, Bertolt transforms into his Colossus Titan, and in the meantime Zeke begins a new assault on the Survey Corps soldiers north of the district, using crushed boulders as projectiles and sending them at devastating speeds into the houses and structures to the north of Wall Maria. This strategy leaves the troops north of the Wall completely immobile, and Commander Erwin Smith joins them to formulate a do-or-die strategy against the Beast Titan. In a last resort, the Survey Corps charges for the Beast Titan using signal flares in an attempt to hinder its vision while Captain Levi maneuvers his way towards the Beast Titan, using the blockade of Titans as a path towards it. The Beast Titan's bombardment nonetheless completely eradicates the charging soldiers, killing and injuring everyone of them except for one recruit. However, in Zeke's distraction Levi successfully ambushes the Beast Titan, completely dismembering it with no time for Zeke to plan a defense. Zeke emerges from his ruined Beast Titan at Levi's mercy, but is soon afterwards rescued by Pieck. Zeke's injuries leave him unable to use his Beast Titan for the remainder of the battle. Four years later, Zeke uses the power of his Beast Titan to transform a group of parachuting Eldian captives into Titans during the battle of Fort Slava at the climax of the Marley Mid-East War, creating a devastating airstrike. Once Reiner joins the combat on the ground and destroys the anti-Titan artillery posing a threat to Zeke's Titan, he transforms into the Beast and uses leftover artillery rounds as projectiles against the navy of the Mid-East Allied Forces stationed in the bay near to the fort. The fleet fires upon the Beast Titan before it is destroyed, but Reiner's Armored Titan saves Zeke from fatal injuries.