At 165cm(5'4), he was the shortest Cadet, and is one of the shortest Garrison members. He has mid-way brown hair, and has dark brown eyes. He often gets picked on by his comrades for his ramen obsession.
Markus' personality is quite mixed actually, he is very honest, brave and serious, but at the same time, is pretty playful, fun and kind with his fellow members, that is, outside of missions. Altough Markus always seems happy and cheerful, he is indeed depressed, considering how many family members of his have died in the hands of titans.
Schildknecht was born and raised in Karanes District, his life was really happy, his Father was a farmer in Wall Maria, and his Uncle worked for the Survey Corps and fought for Humanity's freedom from the doom of titans. Markus was devastated when he was told that Shinganshina District, in Wall Maria, was breached by the Colossal Titan, having to know that his parents have traveled to Shinganshina a couple of days ago, and haven't returned since then figured that they died . The young boy decided then to join the Cadet Corps, and graduate to join the Garrison and avenge his parents.