Man in Black (spy), an alleged "super spy" who made reported assassination attempts on Saddam Hussein and has no sure affiliation with a government

Men in Black, a group of mysterious agents in conspiracy theory

In marbles, any marble, but especially a 5/8" regulation-sized target marble; also a target in a marble game

Milano Italia Borsa, as used in MIB 30 - the main stock market index of the Borsa Italiana

Knoppix-MiB, a version of the Knoppix Linux distribution which focuses on security issues

2-methylisoborneol, a musty-smelling odorant sometimes found in drinking water and cork taint

Management Information Base, a computing information repository used (for example) by Simple Network Management Protocol

Mebibyte (MiB), a unit of information used, for example, to quantify computer memory or storage capacity

Manchester Interdisciplinary Biocentre, a Research Institute within the University of Manchester

Master of International Business

Meiringen-Innertkirchen Bahn, a railway company in Switzerland

Mebibit (Mib), a unit of information used, for example, to quantify computer memory or storage capacity

Medical Information Bureau, a credit agency for life insurers

Melayu Islam Beraja, the adopted national philosophy of Negara Brunei Darussalam

Mint In Box, a collector's abbreviation for an item in mint condition

Men in Black (comic book), a short-lived comic series from Malibu Comics focusing on a group of these agents

Motor Insurers Bureau, a function of the British government which deals with compensation claims from victims of uninsured and untraced drivers

Men in Black (film), an action/comedy movie, and its sequel Men in Black II based on the comic series