Zeke Yeager

Zeke Yeager (in Japanese: ジーク Jīku Yega), otherwise known as the Beast Titan (in Japanese: 獣の巨人 Kemono no Kyojin), is a major antagonist in Attack on Titan and Eren Yeager's half-brother.

He has some connection to the people of Homeland and Reiner Braun refers to him as "Lead Warrior".

Appearance and Abilities
Zeke in Titan form is 17m in stature, larger than the common 15m Titan. While all other Titans seen in the story thus far have been distinctly human in appearance, Zeke's titan form possesses more animal-like features. It has apelike features, and most of its body except for the face and torso is covered in fur.

Zeke possesses numerous abnormal traits while in his Titan form. In his Beast Titan form, he has the ability to speak normal human language. Possibly as a consequence of this, he is capable of controlling other Titans through a combination of verbal orders and physical intimidation. Additionally, the Beast Titan possesses the strength to throw heavy projectiles great distances with excellent accuracy and the dexterity to scale the Wall Maria. He also seems to be a formidable fighter, as he was able to defeat the Armored Titan without sustaining any visible injuries.

He is revealed to possess some unknown means to transform humans into Titans. These Titans are able to function at night, unlike regular Titans.

In his normal human form he has well toned body, has wavy blonde hair along with a beard and mustache. He also wears glasses.

Clash of the Titans arc
The Beast Titan makes his first appearance when Titans are mysteriously appearing within Wall Rose even though the Wall remains intact. He is encountered by Mike Zacharius, who instantly notes the strangeness of his characteristics, mistaking the Titan with a regular Deviant-type. The Titan displays an unexpected behavior when he grabs Mike's horse and launches it at him, preventing his escape and throwing him from the roof he was on.

After Mike falls to the mouth of another Titan, the Beast Titan displays the ability to speak, ordering the other Titans to not eat him so that he can question Mike about the Three Dimensional Maneuver Gear. However, the Titan disobeys him and the Beast Titan crushes its head to release Mike.

The Beast Titan then proceeds to interrogate Mike, but as he neglects to respond out of shock, he theorizes that Mike does not speak due to them not speaking the same language, or Mike being too afraid. After inspecting the gear, he allows the surrounding Titans to devour Mike. As Mike screams in horror, the Beast Titan is amused to see that they did actually speak the same language after all. He finally leaves the scene contemplating the 3D Maneuver Gear.

He next appears walking past Castle Utgard, seemingly ignoring those taking refuge within. Instead, he uses his incredible strength to scale Wall Rose and then disappears.

As the soldiers manage to fend off an attack, he suddenly turns his attention towards them. He begins to break off chunks of the Wall, hurling them long distances at the members of the Survey Corps trapped in Castle Utgard. The first shot kills their horses, and the second kills Lynne and Henning. He then howls, summoning more Titans to continue the assault on the castle. Nanaba angrily notes that he seems to be intentionally toying with them. Afterwards, he climbs over the Wall and disappears into the lost territory of Wall Maria.

When Ymir and Eren Yeager are kidnapped by Reiner Braun and Bertolt Hoover, Ymir states that the Beast Titan is directly responsible for the appearance of Titans within Wall Rose; possibly in order to "test" humanity's strength. She also notes that the reaction of Reiner and Bertolt to his appearance resembled gawking, excited children. She theorizes that locating him must be one of their primary goals and that it is key for them to return to their village.

The Uprising arc
In the aftermath of Eren's failed kidnapping, an investigation is performed at the village of Ragako. The investigation confirms the suspicion that the villagers had been transformed into Titans, though the methods employed by the Beast Titan remains undisclosed.

Two months after Historia Reiss is crowned queen, the Beast Titan is shown in Shiganshina District defeating the Armored Titan in battle. While Bertolt takes out Reiner's body from his Titan form, Zeke emerges from his Beast Titan body, telling Bertolt and Reiner to worry about Annie's rescue later. He then reveals his plan to ambush the Survey Corps in Shiganshina with their help in order to capture Eren and steal the Coordinate, their top priority.

Return to Shiganshina arc
After some time, the Survey Corps initiate the operation to retake Wall Maria. After Eren manages to seal the outer gate of Shiganshina, Zeke, Reiner and Bertolt launch their operation. After Reiner's failed attack and its momentary downfall, Zeke transforms into his Beast Titan form along with a numerous horde of Titans outside the Wall. After that, he picks up a giant boulder and launches it at the inner gate, so that horses could not get over the hole, keeping the soldier from running away. The Beast Titan then roars, ordering small Titans to attack Survey Corps horses, while larger type of Titans form a circle around the entrance of Shiganshina district in order to prevent anyone from escaping the district.

When Reiner gets incapacitated, Zeke is shown talking to Reiner and Bertolt the night before the Survey Corps' arrival. He tells them not to worry about Annie and questions their resolve when they doubt his words. He goes as far as to threaten Reiner with a rematch if they still doubt his decision. He then talks how they need to regain the Coordinate in order to put an end to something he calls the "cursed history." They are shortly after interrupted by a scout Titan who informs them of the Survey Corps' arrival.

Back in present time, incapacitated Reiner roars in his titan form, signaling the Beast Titan to throw a barrel containing Bertolt towards Reiner's location.

he knew Grisha Jaeger when he met Grisha 's son and Half brother Eren

Trivia

 * The Beast Titan's appearance resembles several ape-like cryptids, such as the Sasquatch/Bigfoot, Yeti, and Yowie.
 * The Beast Titan is the first Titan fully capable of advanced communication, speaking the human language effortlessly. It also shows greater dexterity and fine-motor control, allowing it to remove Mike Zacharius's gear without damaging it.
 * Zeke appears to have had limited or no contact with humans inside the Walls for at least half a century, as he expresses interest in humanity's Three Dimensional Maneuver Gear. He also wonders whether or not he speaks the same language as Mike, though it's unknown whether this was genuine or simply mocking his terrified state.