He is depicted with a light brown body, bright blue limbs, and white gloves. He wears a fitness band around the top of his head/body and sneakers on his feet, indicating that he lives an active lifestyle. Toys have depicted him in multiple colors.
Personality-wise, Ollie appears highly energetic and somewhat frantic. In a Camelot-themed puzzle, he is depicted as a court jester, perhaps an indication that he was the comic relief of the group.
His middle initial, "O," implies that his middle name is "Onion," but this is unsubstantiated by the canon.