A black box is a device, object, or system whose inner workings are unknown; only the "stimuli inputs" and "output reactions" are known characteristics.

Black box may also refer to:

• Black box (phreaking), a device to defeat telephone toll charges
• Eucalyptus largiflorens, a tree species with the common name black box
• A descrambling device for cable television piracy

• Accident data recorder, an optional vehicle installable device to record information related to (near) traffic accidents
• Event data recorder, a device installed in some automobiles to record information related to vehicle crashes or accidents
• Flight recorder, an aircraft-borne device used in disaster investigation, consisting of a flight data recorder and cockpit voice recorder
  • Flight operations quality assurance
  • Quick access recorder
• Train event recorder, a device that records data about the operation of train controls and performance
• Voyage data recorder, a device designed to collect data from various sensors on board a ship

• Black box theory, a systems engineering theory for black boxes
• Black-box testing, a form of software testing that involves adjusting inputs to an application without reference to the source code of the application
• Blackbox, a window manager that works on X Window System platforms
• BlackBox Component Builder, software development environment for Component Pascal
• Sun Modular Datacenter, prototype name Project Blackbox

• Any of a number of devices developed and sold by Albert Abrams, based on the pseudo-science of radionics
• Black box warning, a type of warning that may be applied to medicines in the United States

• Black Box (1978 film), an American short film by Scott B and Beth B
• Black Box (2002 film), an Argentine drama film (Caja Negra)
• Black Box (2013 film), an American drama film
• Black Box (2020 film), an American science-fiction horror film
• Black Box (2021 film), a Franco-Belgian mystery thriller film
• Black Box (TV series), a 2014 ABC television series
• Black Box (The Outer Limits), an episode from the 1995 revival of that TV series
• Survival in the Sky, a TV series on the investigations of aviation accidents known as Black Box in the UK
• The Black Box (2005 film), a French mystery film
• The Black Box (serial), a 1915 film serial
• Black Box (video magazine), a Hungarian documentary video magazine and filmmaking group

• Black Box (game), board and computer game
• Blackbox (video game), an iOS puzzle game
• EA Black Box, the video game studio formerly known as Black Box Games
• The Black Box, a canceled video game; See The Orange Box
• A name used to refer to the first thirty games released on the Nintendo Entertainment System

• Black Box (short story), a short story by Jennifer Egan
• Black Box (novel), by Israeli writer Amos Oz
• Black Box (comics) a fictional character in the Marvel Comics Marvel Universe
• Black Box, a novel by Mario Giordano
• Black Box, a memoir by Shiori Itō
• Blackbox (novel) by Nick Walker
• The Black Box (novel) by Michael Connelly
• La boîte noire ("The Black Box"), a Spirou et Fantasio comic album

• Black Box (band), Italian electro-dance music group
• "Black Box" (song), debut single of Australian Idol winner Stan Walker
• A Black Box, an album by Peter Hammill
• Black Box – Wax Trax! Records: The First 13 Years, a Wax Tax Box set album
• Black Box (Brown Eyed Girls album), album by South Korean group Brown Eyed Girls
• Black Box (Naked City album), compilation album by Naked City
• Black Box: The Complete Original Black Sabbath 1970–1978, a Black Sabbath album
• The Black Box (album), a box set album by Danish rock band Gasolin'

• Black box theater, simple unadorned performance space
• Nuclear football, the briefcase that accompanies the President of the United States and contains nuclear missile launch codes, nicknamed "Black Box"
• Censor bars
• Black box trading or algorithmic trading
• Black Box Corporation, a supplier of computer network hardware based in Mumbai, India and Dallas, Texas
• Black box approach to the function of states in international relations in theories such as realism and neorealism
• BlackBox (radio station), a radio station in Bordeaux, France
• Black Box (Handcuff Cover)

• Blackboxing, a social process in science studies
• Black box warning, U.S. warning on a prescription drug
• Black Box Affair, a 1966 Eurospy film
• Box (disambiguation)
• Black body