Sinister Silhouettes

Where The Faceless meets Chekhov's Gunman. It comes in several different flavors, with a common theme. It is an abstract (i.e. not an actual scene) shot of one or more characters, who will eventually be revealed, with said character(s) shown as silhouettes. The background can be anything from bland to suitably ominous, but either way, the Sinister Silhouettes will typically be just standing there in a Badass manner. The background music will most likely be ominous.

This shot is frequently used to either show that the hidden characters are the kind that you wouldn't want to mess with unless you were The Hero or Too Dumb to Live, or to depict them as Shrouded in Myth. May be subverted in that the silhouetted person turns out to be not as badass as had been implied. Typically a trope associated with villainous characters, though it being of The Rival is not uncommon. May have rare heroic cases.

The delivery can go about in a few ways, but most frequently, Alice could just casually mention the name of the Quirky Miniboss Squad. Bob, however, has never heard of them before, and so Alice goes through the trouble of quickly summarizing what she knows about them. As she does, it cuts to a Team Shot of them as Sinister Silhouettes. Said silhouettes being in intimidating poses is optional.

Other methods of presentation include it being shown as part of the Title Sequence or ending credits. Maybe even in an On the Next or Pastel Chalked Freeze Frame.

Compare The Omniscient Council of Vagueness, which is a group of Sinister Silhouettes in an actual, non-abstract scene.

Anime & Manga

 * Jojo's Bizarre Adventure introduces many of its villains this way.
 * The Ginyu Force from Dragonball Z.
 * Silhouettes of Vegeta and Nappa in the first opening sequence are shown doing a Power Walk with fire and lightning in the background.
 * Hellsing: Millennium gets a shot like this in the manga and the OVA.
 * Naruto: The Five Kages, as one would expect from the name
 * The Akatsuki also make their first appearance at the end of part 1 as Silhouettes. Pain's appearance, in particular, isn't shown until well after the first 100 chapters of Part 2.
 * Sailor Moon: Sailor Venus got one in her first appearance, as did the two Outer Senshi Uranus and Neptune.
 * The legendary Digidestined from Digimon Adventure is another heroic case, although they don't show up later on.
 * In the first OP for Digimon Tamers, the evolutionary stages of the Tamers' Mons are shown, but their top levels are shown only as silhouettes.
 * The Gun X Sword Evolving Credits shows Sinister Silhouettes of major characters of both antagonists and protagonists, before they are introduced.
 * Many characters in One Piece, at least in the manga (Zoro, Arlong, the Seven Warlords of the Sea, the Four Emperors, just to name a few).
 * The Seven Warlords in their silhouettes look nothing like they really do. Except for Mihawk maybe. They were also shown to be sword wielders, which doesn't help.
 * Those figures were meant to be Yosaku's idealized mental image of the Warlords. Since Yosaku had never seen any of them except Mihawk, it makes sense that he wouldn't know their appearances. While it's unclear if Oda had designed all of them yet, at that point he had designed at least two (Mihawk and Crocodile) and he knew they wouldn't all be sword users.
 * More than one of the anime openings show characters who have yet to appear in silhouette, and then in later openings with the picture filled in.
 * Revolutionary Girl Utena frequently uses faceless blacked out figures during flashbacks (including the one that opens the narration of every other episode) although their hair and clothes are usually still coloured. This is used for both chilly atmosphere and for presenting it as a fairy tale.
 * The manga of Yu Yu Hakusho does this with Hiei and Kurama (and Gouki, who was unimporant) before we get to know them.
 * The Saint Beasts and Sensui's Seven were depicted in this manner.
 * Best Student Council's OP sequence has a part where each special division of the eponymous Absurdly Powerful Student Council are shown together. While Assault Division has its members performing their signature attacks one after the other, the Vice President for Covert and the Covert commander are shown standing between two silhouettes, the other members of Covert Division. Their faces are revealed after the episodes where they are introduced.
 * The entire Student Council is shown in a Sinister Silhouettes Team Shot before the opening credits start rolling.
 * Parodied in episode 2 of Haruhi-chan. After being defeated by Nagato, Asakura proclaims that though she has been defeated, it's not over yet. She goes on to add that above the Radical Big Four are three leaders, also shown as silhouettes. Kyon proceeds to call her story cheesy.
 * Every suspect gets one of these in Case Closed if the Cold Open decides to show the crime in progress.
 * Samurai Deeper Kyo is the embodiment of Sinister Silhouettes.
 * The Four Kings from Get Backers
 * The Suzaku Seishi in Fushigi Yuugi (with the exception of Tamahome and Hotohori) are first depicted as silhouettes with their body symbols when Hotohori explains the legend of Suzaku.
 * Parodied in episode 38 of Fullmetal Alchemist: Brotherhood, with Yoki imagining himself to be the leader of the Scar gang on a quest for revenge against the Elric brothers.
 * Various openings of Pokémon do this for Gym Leaders or Frontier Brains. Because, you know, the gym leader is totally the one you fight...
 * Fist of the North Star does this with the introduction of Kenshiro's adoptive brothers and then with the six Nanto Stars. The latter is a bit more egregious, since it depicts Shin and Rei alongside four male silhouettes, but one of them later
 * The preview of the third installment of the Rebuild of Evangelion features four shadows that are implied to belong to new Evangelion pilots. Two of them are presumably, but not necessarily Mari and Kaworu, while the other two still remain to be seen.
 * The Netherlands of Axis Powers Hetalia was first depicted as one, until his design was revealed.
 * Flame of Recca had the tendency to introduce the next team of opponents this way.
 * THE iDOLM@STER - Subverted. Kuroi's face is never shown, but the first few times he appears is only his silhouette.
 * The ending credits for Iron Man showed all of the enemies as sinister silhouettes with glowy red eyes, up to and including the Big Bad.

Comic Books

 * Batman does this a lot, on purpose.
 * Since Sin City loves to utilize every noir trope in the book, we get this a lot. Marv is often shown in silohuette with his bandages still visible.

Film

 * In The Lord of the Rings our heroes run into a Sinister Silhouette in the forest. It.

Live Action TV

 * The 'Final Five' in the re-imagined ''Battlestar Galactica.

Video Games

 * The X-Hunters are introduced in Mega Man X 2 as silhouettes observing a hologram recording of X.
 * Also, arguably invoked in X4 by Zero. Invoked as in it's a nightmare the latter was having, yet  looked like he was standing behind a spotlight. And then the "mysterious man" does it again in X5,
 * The original Super Smash Bros plays with this for the opening cinematic. It shows off all the normal playable characters, but the four Secret Characters (Luigi, Jigglypuff, Captain Falcon, and Ness) are only shown as silhouettes until you actually unlock them. Despite the silhouettes and number though, they definitely aren't evil characters by any means.
 * Ishijima Kaigen from the Nitro+ Visual Novel Hanachirasu is only mostly silhouetted, but she makes up for it with Glowing Eyes of Doom. See here
 * Even though it doesn't happen in the context of the game itself, in the manga for The World Ends with You, Kariya and Yoshiro say "Since we appeared in silhouette earlier, you probably thought we were up to something dastardly. We're totally not."
 * Although early in the game, the Reapers do appear, with some slight drak shading over them, so...
 * Although they aren't silhouettes, Organization XIII from Kingdom Hearts invoke this by wearing a hood that obscures their face, revealing their appearance only when Sora meets the individual members properly.
 * In Ace Attorney, the profiles of unknown/unintroduced characters are shown as dark silhouettes, with question marks for their age and profession. A larger version is seen in the first case of Ace Attorney Investigations when a mysterious figure catches Edgeworth at gunpoint in his darkened office--and since the dialogue is completely text we don't even know what gender the person is. It turns out to be

Web Comics

 * About half the cast of El Goonish Shive were introduced with silhouettes. The comic seems to have retired the practice, however, in recent years, likely to make room for other tropes.
 * The Creature Counsil in DMFA meet as a cabal of Sinister Silhouettes... except the Phoenix representive who has an open flame on her head, and cannot lurk in shadows.
 * Loki in The KA Mics likes to appear as a shadowy figure.
 * The Speaker in Harkovast spent the first part of the comic appearing only as a silhouette, while making ominous statements.
 * The Feline Emperor in the Blade of Toshubi has only been seen in silhouette.
 * "What do you expect? I'm just a mysterious shadowy villain"
 * In this Smack Jeeves comic and it's the first comic.
 * Jack Noir often does this in Homestuck. Granted, it's not hard to do, since he has a shiny black carapace.
 * This is the most we ever see of the troll Famous Ancestors, the only colored facial features being mouth, face paint, glasses, and occasionally eyes.
 * This is how Williams's face is kept hidden in Remus once he pulls off his mask. We see eyes, teeth, and knives - that's it.

Western Animation

 * Avatar: The Last Airbender: Fire Lord Ozai for the first two seasons.
 * On Codename Kids Next Door, the first time Father, the Big Bad, appears, he shows up as a silhouette. However, it's quickly revealed that this is because he wears a suit of shadows. For a good deal of the series, even if he appears in broad daylight, he's a silhouette. It's finally ripped off in The Movie...and it turns out we've seen what he looks like in previous episodes.
 * Although it's not that big a surprise. The first episode Father's true appearance appears in made it pretty obvious that was what Father really looked like - although the entire episode was a story made up by Number One. Another episode was a Mirror Universe with that man being the counterpart of Father.
 * The Venture Brothers has the Guild of Calamitous Intent's Council of 13.