Neo Cortex is a very stout human with black hair and unnaturally yellow skin. His eyes are colored black and have bags under them, and he has a black beard. Cortex has balded considerably since his early thirties; there is only a small amount of hair on the top of his head and on the sides and back of his head. One of Cortex's most noticeable features are his large head/forehead, and the "N" on said forehead. By age 48, his hair and beard had started to gray, though most of the 0hair is still black.
He typically wears a white labcoat, but the rest of his outfit changes with his age. From the first game to Wrath of Cortex, he wore yellow rubber gloves, black pants, and black boots. His sleeves were also black. However, Cortex's outfit changed slightly by Twinsanity; his labcoat now had a red "N" logo on it and the sleeves were white, his pants were now white, and his gloves and boots were red with white highlights on them. In Crash Tails, his outfit now consists of a white labcoat (with no symbol on it), black gloves with yellow highlights, black pants, and black boots.