Dennis has medium-length messy brown hair and slight stubble. He also has tannish-colored eyes. He wears the standard Military Police uniform.
Dennis is a lazy, laid-back, high ranking Military Police officer. Like many of the soldiers outside the Scout Regiment, before and after the fall of Wall Maria, he would rather spend his time on the clock drinking and gambling. When given the opportunity he quickly shirks his duties onto those below him in rank.
It is revealed shortly after this happens that he shirked his duties to his subordinate in order to gamble, drink, and play cards instead.
After Annie Leonhart reveals herself as the Female Titan, he is seen among several other Military Police soldiers attempting to hurriedly put on their omni-directional mobility gear when Eren and Annie run by in Titan form. He is later seen alongside Erwin and Nile following Annie's capture, indicating that he survived almost being trampled by her and Eren.