Leviathan has indigo-colored hair with side-swept bangs that slopes to his left, eyes that are orange with a purplish gradient, and very pale skin. Like all of the demon brothers, he has painted nails that are sometimes cyan and sometimes dark indigo. He and Asmodeus are the only brothers with an inconsistent nail color.

Despite being shown to have defined abs, Levi is very out of shape. He can't jump rope and run one lap around the House of Lamentation in the Devilgram Love, Friendship, and Ju