Masters of Disguise

A Master of Disguise is character who can be anybody during the course of the story. Giving a character this power and concealing its use from the audience for a "reveal" is very hard to pull off.

They may rely on extensive training and a vast collection of wigs, clothing and stage makeup to pull off the fakery. Or, their powers could be Phlebotinum-driven, in that they have the physical ability to alter their very shape and size to perfectly match that of the person they are duplicating.

Expect them to be called "The Chameleon" (even if real chameleons cannot hide themselves) and to be crucial to an "Impossible Mission".

Their allegiances can go either way. Sometimes they are villains, sometimes they are heroes (though not usually The Big Bad or The Hero themselves), and very often they're just Wild Cards.

See also Convenient Color Change; Latex Perfection; Master of Illusion; Shapeshifting; Wig, Dress, Accent; We Will Not Use Stage Makeup In The Future; The Power of Acting. Compare Clark Kenting. Master Actor is a subtrope that covers only the acting. Man of a Thousand Faces is when an  Actor  is a Master of Disguise. Someone may be Cast as a Mask.

Not all villains go as themselves through the entire work of fiction, some of them go in another form (or alter-ego) to hide their identity.

Please note that (A) this should not be confused with Happy Madison Production's  The Master of Disguise  and that (B) Black Hat refers to this technique as "the Skinwalker".

Examples

 * Ursula disguised herself as Vanessa, a young maiden with Ariel's stolen voice.
 * The Emperor of the Night disguised himself as the Boatman, the Doorman, and the Ringmaster. All of these forms were used to deceptively welcome "guests" into his dark kingdom.
 * The Evil Queen concocts a potion to herself into a hideous old witch, to pretend as some mere beggar woman in order to fool Snow White.
 * Balthazar Bratt disguised himself as the President of the United States and later Lucy Wilde.
 * Aku disguised himself as Ikra.
 * Dr. Jacques Von Hamsterviel disguised himself as Professor Gunter Free.
 * Zartan, The Baroness, and his sister, Zarana disguises themselves as any citizen.
 * The Chameleon is a shapeshifting sneaky lizard who disguises himself as any citizens or objects in Petropolis.
 * The Decepticons disguises themselves as a variety of vehicles, as any Transformer can do. For example:
 * The Generation 1 incarnations of Megatron and Shockwave transformed into weapons for other Decepticons to use, though later appearances gave them Cybertronian vehicle modes. Similarly, Generation 1 depicted Soundwave as transforming into a boombox before later appearances gave him a truck/SVU-type vehicle mode.
 * Starscream and all Decepticons sharing the same body-type as him, including Thundercracker, Skywarp, and Ramjet, transform into jet fighters.
 * Constructicons such as Scavenger, Long Haul, Mixmaster, Scrapper, Bonecrusher, and Hook can transform into construction vehicles.
 * Stunticons such as Motormaster, Drag Strip, Breakdown, Dead End, and Wildrider transform into stunt vehicles.
 * Combaticons such as Onslaught, Swindle, Brawl, Vortex, and Blast Off transform into military vehicles.
 * Triple Changers such as Blitzwing and Astrotrain possess two vehicle modes instead of just one.
 * Soundwave's cassette 'bots (later called "Mini-Cons") mostly consisted of robotic animals that turned into cassette tapes, such as Laserbeak (a condor), Ravage (a jaguar), Ratbat (a bat), and Buzzsaw(an eagle). They also had Rumble and his twin Frenzy, who turned from small humanoid robots to cassette tapes.
 * Makeshift is a special kind of Cybertronian dubbed a "Shifter", who can transform into any other Cybertronian. He once disguised himself as the Autobot Wheeljack.
 * Queen Chrysalis disguises herself as Princess Cadence.
 * Bowser Jr. disguises himself as shadow Mario to vandalize Isle Delfino in order to frame Mario.
 * Sheldon J. Plankton disguises as any of SpongeBob's friends or his family members in order to steal the Krabby Patty formula.
 * Cato Parasitti disguises herself as a Jedi master in order to infiltrate the Jedi Temple.
 * Romeo (from Minecraft: Story Mode) disguises himself as Vos and later Jesse.
 * Demaro Black and his crew impersonated Straw Hat Pirates.
 * Lasombra disguised himself as Eduardo in order to lure Arnold and his class into his hideout so he could take them as his prisoners.
 * Nohayas disguises himself as a knock-off version of Prohayas and tries to steal his identity.
 * Zoisite disguised himself as Sailor Moon to get Tuxedo Mask. In Sailor Moon Crystal, he disguised himself as Dr Isono to brainwash people to get the Silver Crystal before the real Tuxedo Mask intervene.
 * Nephrite disguised himself as the Attendant.
 * Gellert Grindelwald disguised himself as Percival Graves.
 * Vexus disguised herself as photographer, Vee, QT2, Violet and Vicky.