MU, Mu or μ may refer to:

• Aries Mu, a character from the anime Saint Seiya
• Mu La Flaga, a character from the anime Mobile Suit Gundam SEED
• Monsters University, a 2013 animated film by Disney and Pixar
• "μ's" (pronounced "Muse") is the name of the protagonist school idol group in the anime series Love Live!.

• Mu Online, a 2003 online role-playing game
• Mu, an ancient civilization from Mega Man Star Force 2.
• Mu-12, a character from the BlazBlue series
• Colony Mu, a location from Xenoblade Chronicles 3

• Mu (album), a pair of free jazz albums by Don Cherry, released in 1969 and 1970
• Mu Performing Arts, an Asian-American theater company and taiko drumming ensemble
• MU (musician), Mutsumi Kanamori, a Japanese-British musician
• MU, musical group formed by Merrell Fankhauser and Jeff Cotton
• M.U. – The Best of Jethro Tull, a greatest hits album
• Planet Mu, an electronic music label
• Mu Vol. I, is an EP album by Richard Henshall, released in 2024. It is part of a trilogy.

• Mu Dynamics, a company which makes hardware and software to test network services
• MU Press, an independent comic book publisher
• Isuzu MU Wizard, a compact sport/utility vehicle
• Micron Technology, Boise, Idaho, US, NASDAQ symbol
• China Eastern Airlines, Shanghai, China, IATA code

• Mu (letter) (Μ or μ), the 12th letter of the Greek alphabet

Micro- (μ), metric prefix for one millionth

• Mu (kana), む or ム, a Japanese kana
• Mu (cuneiform), a sign in cuneiform writing
• Mu (negative), a word meaning "no" or "without" (Japanese: 無; Korean: 무)
• Middle Ukrainian, Ukrainian language 16th–18th century

• Mothers' Union, a global Anglican women's organisation
• Musicians' Union (UK)
• Groupe μ, Belgian linguistics group

• Mu River, a river in Burma (Myanmar)
• Mu River (Hokkaidō), a river in Japan
• Mù, a village in the Edolo municipality of Italy
• Mauritius (ISO 3166-1 alpha-2 country code MU)
  • .mu, the country code top-level domain for Mauritius

• Mu (mythical lost continent), a mythical continent in the Pacific Ocean

• Mu (surname) (穆, 牧, 慕, 木, 母, 目, 沐, 睦 and 暮), Chinese surnames
• Mu family, a powerful Chinese family from the 14th to the 18th century
• Mu of Baekje (580–641), king of Baekje
• Mu of Balhae (died 737), king of Balhae from 718 to 737
• Marquis Mu of Cai, ruler of the state of Cai from 675 to 646 BC
• King Mu of Chu (died 614 BC), king of the state of Chu from 625 to 614 BC
• Emperor Mu of Jin (343–361), emperor of the Eastern Jin Dynasty
• Marquis Mu of Jin (died 812 BC), ruler of the state of Jin from c. 798 to 776 BC
• King Mu of Zhou (died 922 BC), king of the state of Zhou from c. 976 to 922 BC
• Mu Dan (1918–1977), Chinese poet and translator
• Athing Mu (born 2002), American middle-distance runner

• Mu (negative), 無, a concept in Buddhism
• Muism (Korean shamanism), the native religion of Korea
• Mu (shaman), a Korean priest
• Church of England in Hunters Hill, New South Wales, Australia ("early church code" used by NSW Registry of Births Deaths & Marriages)

• Mu phage, a bacteriophage of the family Myoviridae of double-stranded DNA non-enveloped contractile tail bacterial viruses
• Centimorgan, or "map unit", a unit of recombinant frequency in genetics
• Monitor unit (MU), a measure of absorbed dose from a linear accelerator in radiation therapy = 0.001 Gray
• SARS-CoV-2 Mu variant, one of the variants of SARS-CoV-2, the virus that causes COVID-19
• Mouse unit, the amount of toxin required to kill a 20g mouse in 15 minutes via Intraperitoneal injection

• Chemical potential, a form of potential energy that can be absorbed or released during a chemical reaction
• Bridging ligand, an atom that connects two or more metal centers in a complex (molecule)

• MU puzzle, a puzzle in the book Gödel, Escher, Bach
• Minimalization operator (M operator), a function-building operator for General recursive function
• Möbius function, a multiplicative function in number theory and combinatorics
• Degree of membership in a fuzzy set
• The standard measure function name in measure theory
• Complex cobordism, an extraordinary cohomology theory

• Micro-, SI (metric, "μ-") prefix denoting a factor of 10⁻⁶ (one millionth)
• Micrometre (deprecated as a single-character symbol "μ" for micron)
• Million units of energy, a term used in India for a gigawatt-hour, see kilowatt-hour#Other related energy units
• Mu (land), a Chinese unit of area also spelled "mou", equivalent to about 0.066 hectares.

• Coefficient of friction, used to approximate the force of friction
• Deformation (physics), as the "unit" of strain
• Electron mobility, relating the drift of electrons to the applied electric field across a material
• Linear density, a measure of mass per unit of length
• Magnetic dipole moment, a measure of the strength of a system's net magnetic source
• Mu-metal, a nickel-iron alloy with high magnetic permeability
• Muon, an elementary particle
• Muonium, exotic atoms made up of an antimuon and an electron
• Permeability (electromagnetism) coefficient, degree of magnetization of a material
• Proton-to-electron mass ratio, a dimensionless physical constant
• Reduced mass, the "effective" inertial mass appearing in the two-body problem
• Standard gravitational parameter of a celestial body
• Viscosity, the resistance of a fluid which is being deformed by stress

• μ, in evolutionary algorithms, the population size from which in each generation λ offspring will generate
• Mu (rocket family), a Japanese rocket family launched between 1966 and 2006
• Multiple unit, self-propelled train carriages capable of coupling with other units of similar type
• Olympus mju (stylised as μ[mju:]), series of a compact cameras
• The mu (μ) ring of Uranus

• Metropolitan University (disambiguation)

• Macquarie University, Sydney, New South Wales
• Monash University, Melbourne, Victoria
• Murdoch University, Perth, Western Australia

• Madras University, Chennai
• Mumbai University
• Manipur University, Imphal

• Marquette University, Milwaukee, Wisconsin
• Marymount University, Arlington, Virginia
• Maryville University, Town and Country, Missouri
• Marshall University, Huntington, West Virginia
• Messiah University, Mechanicsburg, Pennsylvania
• Millersville University of Pennsylvania, Millersville, Pennsylvania
• University of Missouri, Columbia, Missouri

• Mahidol University, Salaya, Thailand
• Mandalay University, Mandalay, Myanmar
• Masaryk University, Brno, Czech Republic
• Meiho University, Pingtung, Taiwan
• Misamis University, Ozamiz City, Misamis Occidental, Philippines
• Mondragon University, Mondragon, Spain
• Mzumbe University, Mzumbe, Tanzania

• Musician (United States Navy), an enlisted rating
• Mu, a type of icicle radish
• Manchester United F.C., a British football club
• Miss Universe, international women's beauty pageant
• MuseScore, a sheet music notation software
• /mu/, a board pertaining to music discussion on 4chan

• Moo (disambiguation)
• M (disambiguation)