A cukoloris is a flat opaque object with holes in it. It is held in front of a light to make a pattern of shadows on the subject, such as tree branches. It can be constructed out of styrofoam, wood, or cardboard, or if it is meant to be mounted very close to the light, even metal. It's sometimes spelled cucoloris, kookaloris, cookaloris, or cucalorus. The word cukoloris is Gaelic and means "ghost charm." How a Gaelic word became a standard term in film production is unknown.

The name is often shortened to "cookie," a usage which is probably reinforced by the fact that a cukoloris "cuts holes" in a beam of light much like a cookie cutter cuts cookies from a sheet of dough. A similar device in theater stagecraft is called a "gobo," supposedly short for "'''go'''es '''b'''efore '''o'''ptics." A gobo is inserted between the actual lamp and a focusing lens, permitting a much more focused image from the gobo, in the manner of a slide projector. A "cookie" would instead be hung after the lens and produces an indistinct shadow.

It can also refer to a flickering light source or reflection, to suggest, say, a pile of gold or glowing orb of power lighting up the faces of the actors. The gold itself need not be visible to the audience.

Used in any number of high tech shows and movies in which a computer display seems to be projecting its screen image onto the user's face. It's not entirely accurate, but [[RuleOfCool that's not why they use it in the first place]].
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!!Examples

[[folder:Films -- Live-Action]]
* ''Film/TwoThousandOneASpaceOdyssey'' was the first movie to show computer monitors projecting their images onto the user's face. This is pure RuleOfCool, because in order to get this effect in real life you'd have to be staring straight into the bulb of a projector. There were 16mm projectors behind all the flatscreens on the sets, so all Kubrick had to do was take the screens off.
%% commented out as ZeroContextExample * ''Film/{{Alien}}''
%% commented out as ZeroContextExample * ''Film/BatmanAndRobin''
* In ''Film/CityOfTheDead'', inside the Raven's Inn, a pronounced "roaring fire" effect is applied to the walls.
%% commented out as ZeroContextExample * Creator/DavidLynch's ''Literature/{{Dune}}''
%% commented out as ZeroContextExample * ''Film/DeathMachine''
* In the flashback scene of ''Film/FangsOfTheLivingDead'', weird patterns are projected on the walls of Malenka's laboratory.
%% commented out as ZeroContextExample * ''Film/GuardiansOfTheGalaxy''
%% commented out as ZeroContextExample * ''Film/{{Swordfish}}''
%% commented out as ZeroContextExample * ''Film/SuckerPunch''
%% commented out as too general per HowToWriteAnExample * Creator/StevenSpielberg is fond of using these with underlighting to illuminate a character's face when seeing a reflective object. Particularly noteworthy as an effect used when Franchise/IndianaJones is uncovering a golden or glowing idol or artifact.
* A short scene in ''Film/{{Tombstone}}'' involving a traveling show features a decidedly low-tech version, where the effect of flickering flame (symbolizing FireAndBrimstoneHell in a reading of Faust) is created by having a stagehand slosh a half-full bottle of whiskey in front of the light.
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[[folder:Live-Action TV]]
* A "flickering light source" version is the Stargate in the ''Franchise/StargateVerse''. To avoid CGI costs, the open gate is in many shots offscreen but its flickering light -- produced by a stagehand warping a flexible mirror -- illuminates the rest of the scene, and sound effects do the rest.
%% commented out as too general per HowToWriteAnExample * ''Series/StarTrekTheOriginalSeries'': Though not exactly "an opaque sheet with holes in it," shadows from devices like these were often used to suggest structural detail that's off camera (and so doesn't have to actually be built). Look in the "overhead" area of the ship's interiors, particularly where a corridor opens onto a larger junction.
* ''Series/DoctorWho'':
** In the episode "[[Recap/DoctorWhoS6E5TheSeedsOfDeath The Seeds of Death]]", the launch countdown is projected onto Gia's face.
** For their (now-lost) story "The Myth Makers," the BBC used the Trojan horse's shadow, and model shots of the horse, to avoid the cost of building a full-size version.
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