Until I'm sure that you've been shown
That I can be trusted walking with you alone
The phrase "wolf in sheep's clothing" pertains to a character who disguises themselves as nicer or more harmless than they really are to conceal their true identity, feelings, or motives. Characters that are disguised this way might not necessarily be evil or intend malice, but when their lie is discovered it usually causes at least feelings of betrayal and distrust.
Sister trope to Obfuscating Stupidity, Obfuscating Insanity, Obfuscating Disability, and Crouching Moron, Hidden Badass, all of which also involve presenting themselves as less of a threat in various permutations. Compare with Face of an Angel, Mind of a Demon, where an evil character looks like a good one, but whose appearance is not necessarily an affected disguise, and who is definitely evil rather than simply dangerous. Contrast Beware the Nice Ones, when the character actually is nice until you push them too far.
A form of Hidden Depths or Beneath the Mask. Often employed by The Mole in The Infiltration. If everyone is putting on a mask they are a Flock of Wolves. When this trope is performed literally, that is Ass in a Lion Skin.
Surprisingly not related to Sheep in Wolf's Clothing, which is when someone is partly turned into a monster but retains enough humanity to work against the monsters.
- Blackbeard in One Piece to Whitebeard's crew.
Jinbe: Ever since he was on old Whitebeard's ship, no one's ever known his true nature.
- Rurouni Kenshin: Saitou's "Fujita Gorou" persona is pleasant, unassuming, and literally forehead-to-the-floor humble. In reality he's a Good Is Not Nice Jerk Ass. The interesting thing is that it's not just for his undercover work; that's his civilian identity as well.
- Most of the Homunculi from Fullmetal Alchemist. Special mention goes to Lust and Pride, who manage to fool various members of the military and the protagonists.
- In Tokyo Ghoul, ghouls that don't actively shun human society do this out of necessity. A predator living among their prey, they must work to constantly maintain a normal and harmless persona to avoid being discovered and hunted down by the authorities. Those that go a step further and maintain a human identity are said to be walking a tight-rope, always having to keep their predatory instincts in check and avoid doing anything that could give them away. Sadly, it doesn't matter if their kindness is genuine or not. After all, ghouls aren't really people, right?
- The Far Side did this a few times (being the Trope Namer for Flock of Wolves). Although sometimes, the wolves didn't exactly get it right:
Wolf: Hey, that's a good idea. "Sheep's" clothing. Let's get out of these gorilla suits!
- One Bizarro had a wolf dressed as a sheep confessing to a therapist that he's not wearing it to catch sheep anymore. It's the real him.
- Blood and Revolution: Saitou, as with his canon counterpart, takes on unassuming and pleasant personae to deal with politics and go undercover. Fujita Gorou was probably the longest running (as it was his civilian persona) but Ichinose Denpachi deserves special notice for changing his personal pronoun consistently to 'boku'.
- The animated version of the Three Little Pigs had the The Big Bad Wolf attempt to enter the second pig's house by pretending to be a baby sheep. The two little pigs don't buy it.
Wolf: "I'm a poor little sheep, with no place to sleep. Please open the door, and let me in!"Pigs: "Not by the hair of our chinny-chin-chin! You can't fool us with that old sheepskin!"
- The expression is referenced in Zootopia in the form of a Visual Pun, where near the end Chief Bogo assigns a trio of officers to undercover, and the wolf of the group puts on a disturbingly convincing sheep costume.
- Hoodwinked also does this with a Visual Pun. Namely, the Wolf and Twitchy disguise themselves in sheepskins to infiltrate a flock and talk to a sheep that is one of the Wolf's best sources of information.
- Inverted in the Darkest Powers series by Derek Souza. He's standoffish and can be utterly tactless at times, but he's also a genuinely good person who still carries the guilt of the one time he accidentally hurt someone in self-defense. However everyone, including a family friend who's known him from childhood, assumes he's a violent thug pretending to be harmless. The humans fear him because he's over six feet tall and 220 pounds of solid muscle at the age of 16, and the supernaturals fear him because he's a werewolf. In short: Derek is usually assumed to be a wolf in sheep's clothing when, metaphorically, the opposite is true.
- In Dragon Bones, there is an individual who pretends to be a harmless escaped slave, while she's actually magically enslaved and working for her master all the time. She is actually quite a nasty person, but pretends to be nice.
- A Song of Ice and Fire, (being an entire series worth of Doorstopper sized Gambit Pileups), has no shortage of these, but one character who stands out for this trope is Petyr "Littlefinger" Baelish. He's an interesting example because he doesn't pretend to be nice (his affable persona is a deliberately Paper-Thin Disguise); the real pretence is that he acts like a Smug Snake when he is in fact a full-fledged Magnificent Bastard, so still fits the bill of pretending to be much less dangerous than he really is.
- Famously in Little Red Riding Hood, The Big Bad Wolf tricks the title character by dressing in her grandmother's nightgown. "My, grandmother, what big teeth you have!"
- In River of Teeth, Archie, a cunning thief and conwoman, likes to disguise herself as a proper lady because nobody ever suspects a fat woman in a custom-made dress to have such nimble fingers.
- Geryon, a monster from The Divine Comedy who guards Eighth Circle of Hell, is the biologically manifestation of fraud. It may have the face of a beautiful man, but behind that face is the body of a massive winged serpent with a tail ripe with venom.
- Invoked if not actually used by the characters themselves in Airwolf. The design concept was a supersonic attack helicopter whose weapons were hidden in pods so it could pass as a fancy executive transport. The flight suits' shoulder patches even featured a Wolf In Sheep's Clothing design.
- The Frankenstein Chronicles: Lord Daniel Hervey, who initially comes off as a kindly physician concerned that the Anatomy Act may outlaw his practice (which is charitable for the poor) and implied to share his sister's religious objections as well. However, it turns out that he is a multiple murderer who experiments on raising the dead with kidnapped children. Oh, and he's also an atheist.
- Daredevil: This trope aptly describes Marci Stahl. Marci is the only white collar attorney we've seen across Landman & Zack or Hogarth Chao & Benowitz who actually shows compassion and selflessness towards others and isn't willingly engaging in illegal activity, and puts up a selfish front because she doesn't want to be seen as weak.
- In the song "Little Red Riding Hood" by Sam the Sham and the Pharaohs, the singer (in the role of the wolf) mentions wearing a "sheep suit" to win the trust of the girl. It concludes with the wolf howling and then correcting himself: "I mean baaaaaaa! Baaaa!"
- The aptly named song "Wolf in Sheep's Clothing" by Set it Off describes such a character, although by the Tv Tropes definition it actually seems to refer to a Bitch in Sheep's Clothing.
- From a sermon by Jesus recorded in the Christian Bible: "Beware of false prophets, which come to you in sheep's clothing, but inwardly they are ravening wolves" (Gospel of Matthew, 7:15 — King James Version). The sermon then suggests that their true nature will be revealed by their actions (by their fruits shall ye know them, verse 16).
- Petrus of Thorouland from Dark Souls quotes this word-by-word if you get killed by him when you attempted to avenge Reah.
- Done literally in Sheep, Dog 'n' Wolf: the player character (Ralph Wolf) can acquire and wear a sheep costume, and uses it to steal sheep.
- Renon from Castlevania 64 openly introduces himself as a demon, but reassures you that since one "needs gold even in Hell these days" that he'd rather exploit the niche market of adventurers who need supplies in the titular castle. Throughout the game he is polite, gentlemanly, and has a real habit of leaving the contract necessary to summon him wherever you need it. While it's possible to only see this side of him, he neglects to tell you about the contract's fine print: spend more than $30,000 and he owns your soul. If this happens he goes full One-Winged Angel and becomes a rather gruelling Bonus Boss intent on taking what is now his.
- Played with in multiple fashions in Kevin & Kell, particularly in the relationship between Corrie (a sheep note ) and Bruno (a wolf). Corrie spent a period as a sheep in wolf's clothing, since Bruno's best friend Rudy was opposed to carnivore/herbivore relationships.
- Zero Percent Discount has such a wolf but he gets killed by a Threatening Shark.
- Juvenile piranhas insinuate themselves into schools of other fishes, finding safety from larger predators in the crowd. They also feed off their non-piranha schoolmates, biting off pieces of the fins of unsuspecting companions.
- Some types of livestock-guarding dog, such as the Great Pyrenees or Kuvasz, have been bred to look like sheep so they won't scare the herds they're supposed to be protecting. This also hides them from wolves, who get a surprise when the dog interferes with their hunting.
- In the United States Air Force, there is an entire Fighter Wing that earned its nickname from an operation based on this concept. During The Vietnam War, North Vietnamese MiGs were pouncing on American F-105 Thunderchiefs, older, clumsier fighters that had been relegated to doing bombing missions. The 8th Tactical Fighter Wing, under the leadership of Robin "The Wolf" Olds, launched an operation where F-4 Phantoms would fly the same routes as the F-105s, flying close together so that two Phantoms would resemble a single Thunderchief on the North Vietnamese pilots' radar. When the unwary North Vietnamese pilots closed to engage what they thought were vulnerable bombers, they realized, often too late, that they had blundered into an ambush. Ever since then, the 8th TFW (now simply known as the 8th Fighter Wing) has been called "The Wolfpack."
- Q-ships are another example of this concept, merchant vessels with a disguised armament intended to lure enemy submarines into attacking them while surfaced. The flip side and more literal version of this is a merchant raider, a similarly fitted warship that attacks shipping. Both of these systems were used by the British and Germans respectively during World War I.
- "Sleeper" are high-powered cars with restrained styling, usually using the bodywork of a normal vehicle. The 2003 Mercury Marauder was a modern four-door 300hp+ muscle car, that shared the same body as a run-of-the-mill Ford Crown Victoria - a Boring, but Practical police cruiser and taxi - the only thing identifying it as a sports car being the dual exhaust. Tuning can turn even the most unassuming cars into speed monsters, such as this Honda Insight blowing the doors of a V8 Camaro.
- Israeli Prime Minister Benjamin Netanyahu has used this analogy word-for-word to describe openly moderate Iranian President Hassan Rouhani (claiming his predecessor, the far-more conservative Mahmoud Ahmadinejad, was a blatant "wolf-in-wolf's clothing").