The Beast Titan is an extremely unusual specimen, having a distinct ape-like appearance. Its body structure and facial features are like that of a human, it walks upright like one also. It stands at a previously unseen 17 meters in height.
Dark fur covers the large majority of its body, with the exception of its face, hands, feet, and torso. Its arms are also elongated, with long fingers and a fully-functional thumb. The proportions of its upper body are similar to that of the Colossal Titan, possessing a massive chest and small head, as well as unusually slim arms.
The Beast Titan makes its first appearance when Titans are mysteriously appearing within Wall Rose even though the Wall remains intact. The Titan displays remarkable intelligence in its encounter with Mike Zacharius. It prevents his escape by killing his horse and ordering the other Titans not to eat him so that it can question him about the 3D Maneuver Gear. It takes Mike's gear to examine when he neglects to respond, which the Beast Titan theorizes is 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 speak the same language after all. 
As the soldiers manage to fend off an attack, it suddenly turns its attention towards them. It begins to break off chunks of the Wall, hurling it long distance at members of the Survey Corps trapped in Castle Utgard. The first shot kills their horses, and the second kills Lynne and Henning. It then howls, summoning more Titans to continue the assault on the castle. Nanaba angrily notes that it seems to be intentionally toying with them. Afterwards, it climbs over the Wall and disappears into the lost territory of Wall Maria. Connie Springer, Reiner Braun and Bertolt Hoover notice the Titan, seeing the damage it caused, and openly wonder its origins.When Ymir and Eren Yeager are kidnapped by Reiner and Bertolt after the revelation of their identities, 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, also noting that the reaction of Reiner and Bertolt to its appearance resembled gawking, excited children.  She reveals that locating it must be one of Reiner and Bertolt's primary goals and is key for them to return to their village.
In the aftermath of Eren's failed kidnapping by his former comrades, 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 remain undisclosed. 
Unlike other Titans, it is seen to be able to fully speak the human language, casually talking to other Titans and even giving them orders. It is the only non-Titan Shifter known to fluently speak the human language. It possesses great physical strength, sufficient enough to break off large chunks from Wall Rose and hurl them at a great distance away.
It is revealed to possess some unknown means to transform humans into Titans. These Titans, unlike regular Titans, were capable of functioning at night. As many houses showed signs of the transformations taking place indoors, it does not appear that immediate physical contact is required.
- The Beast Titan's appearance resembles several cryptids, such as the Sasquatch/Bigfoot, Yeti, and Yowie.
- It appears to have had limited or no contact with humanity for at least half a century, as it expresses interest in humanity's 3D Maneuver Gear. It also wonders whether or not it speaks the same language as Mike, though it's unknown whether this was genuine or simply mocking his terrified state.
- The Beast Titan is the first Titan fully capable of advanced communication, speaking the human language effortlessly. It also shows greater dexterity, in allowing it to remove Mike Zacharius's gear without damaging it.
- It ranks 3rd on the Titan Popularity Poll.
- It makes an appearance in Attack on Titan: The Last Wings of Mankind.
- The Beast Titan refers to itself as being "in the neck", suggesting that it may be a Titan Shifter or referring to the "human pilots" of all Titans in general. Its exact nature, however, remains therefore a mystery.