At the beginning of the movie, Ashitaka is depicted as a handsome young man who has long hair that is tied into a bun, but he cuts it off after he is told to leave the village. His hair then has a layered cut with wild bangs cut over his eyebrows. His hair is naturally brown and has blue eyes. His clothing consists of a blue top and peach-white pants, as well as brown bottom warmers and shoes made out of fabric. He also wears blue arm sleeves and a red hood to cover his face. He wears a cloak made out of hay for a small portion of the movie. He wears his fiancée's crystal dagger (In the village, everyone calls each other brother and sister, even if they are not related) before he gives it to San. After San's attack on Iron Town, Ashitaka has a slash scar on his left cheek where San slashed him with her dagger.
His curse often manifested as a glowing blue and black aura on his right arm. This signified his anger or the anger of those around him, and occasionally caused the muscle mass of his arm and body to momentarily increase. The aura itself often appeared similar to the demon curse that initially infected his body.
Ashitaka is very stern and determined to achieve his goals, not allowing his setbacks to stop him from curing his curse and saving his village. He is also extremely curious in nature, wanting to discover who San truly is after witnessing her sucking venom out of one of the wolves. Despite his hard outer shell, Ashitaka is also very kind and only wishes for the best outcomes for both sides, not wishing for either side to shed blood in destructive wars, and wants peace between the forces of nature and humanity.
His affinity for peace is portrayed several times throughout the movie. One example of his tendency to only fight as a last resort is his interruption of San and Eboshi's fight. Even though both are attacking him, he initially tries to convince them that hatred is blinding them, and when he's further attacked, he dispatches them in a non-lethal manner.
On top of that, after stating that he will leave and take "the wolf girl" with him, he is shot in the back by one of the villagers, to which he simply moves on, without retaliation, further displaying no interest in actions that would lead to continued violence.
He also has romantic feelings towards San, viewing her as the most beautiful woman he'd ever seen his life.