A disguise can be anything incognito which conceals one's identity or changes a person's physical appearance, including a wig, glasses, makeup, fake moustache, costume or other items.
Protests often feature people dressed in humorous costumes while political publicity stunts and pranks sometimes employ disguises and imposture.
For example, Superman passes himself off as Clark Kent, and Spider-Man disguises himself in a costume so that he cannot be recognized as Peter Parker.
In Marvel Comics, a common enemy of Spider-Man is The Chameleon, whose main tactic is his ability to easily blend into crowds, change his voice, and make masks that look identical to other people.
Examples include dressing as a peddler in order to avoid being spotted on the moor so that he could get his investigative work done in The Hound of the Baskervilles, or as an Indian sailor so that he could speak with Professor Moriarty about his evil plan in Sherlock Holmes and the Secret Weapon.
Robots can also commonly pass themselves off as human using a realistic outer skin, sometimes leading to a plot twist if a character is revealed as an android.