A disguise can be anything which conceals or changes a person's physical appearance, including a wig, glasses, makeup, fake moustache, costume or other items. Camouflage is a type of disguise for people, animals and objects. Hats, glasses, changes in hair style or wigs, plastic surgery, and make-up are also used.

Disguises can be used by criminals, terrorists, and secret agents seeking to avoid identification. A person working for an agency trying to get information might go 'undercover' to get information without being recognised by the public; a celebrity may go 'incognito' in order to avoid unwelcome press attention. In comic books and films, disguises are often used by superheroes, and in science fiction they may be used by aliens. Dressing up in costumes is a Halloween tradition.