Bertholdt is a quiet, young man, identifying himself as someone with a weak will that follows popular opinion. Likewise, their instructor noted him to be a person with great potential, but an utter lack of initiative. He is further described by Eren as being taciturn, and tends to remain in the background unless necessary. By his own admission, he is something of a coward and his official ratings note him to possess a "self-esteem" of a 1 or 2, out of 10.
However, it is also revealed that he can be incredibly cold towards others. When confronted by Eren over his crimes, he merely states that it was "unfortunate" and shows little remorse. On the other hand, he shows great concern and distress when it comes to Reiner.
A p p e a r a n c eHuman FormBertholdt is a rather tall, slender young man. He has short, dark hair and green eyes. In the anime adaptation, he has a slightly darker tan.
Titan FormAs the Colossal Titan, he possesses a very distinctive appearance and a number of unusual features. First of all, it is roughly 60 meters tall, making it around four times the height of any other Titan seen thus far in the series.
Bertholdt's Colossal Titan form is one of the more heavily deformed Titans seen in the series - it appears to lack skin entirely and its jaw and facial structure seem to be heavily altered from the human form. It is also constantly releasing jets of steam from the surface of its body, in a manner that parallels Bertholdt's frequent nervous sweating. Its feet are also quite different to those of a human and other Titans, as they are swollen and pillar-like in appearance. Its physiology is modeled after the male gender, but like all Titans, it lacks obvious sexual organs.