Tau (Τ or τ) is the 19th letter of the Greek alphabet. Tau may also refer to: Mathematics Tau (mathematical constant), a circle constant equal to (6.28318...) Tau test in statistics (tau-a, tau-b and tau-c tests or Kendall tau rank correlation coefficient) Tau function (disambiguation), several Geography Tau, Norway, a small town in Strand municipality, Rogaland county, Norway Tău (disambiguation), two villages in Romania Ta‘ū, an island in the Manua Island Group of American Samoa Ta'u County, a county in American Samoa Tau (Tongatapu), an island of the Tongatapu group in Tonga Tau (Haapai), an island of the Haapai group in Tonga Tau (Botswana), a village at the base of the Tswapong Hills in Botswana Science and technology TAU (spacecraft), a proposal to send a space probe to a thousand astronomical units from the Earth Tau (particle), also called Tau lepton, an elementary particle in particle physics Tau emerald, a species of dragonfly Tau neutrino a subatomic elementary particle Tau protein, a biochemical protein associated with microtubules Tau, the standard astronomical abbreviation for Taurus (constellation) Tau, a mutation in the Casein kinase 1 epsilon protein, in circadian biology Rational Tau, a UML and SysML modeling tool Opsanus tau, the scientific name for the oyster toadfish Arts and media Tau (film), a 2018 thriller film starring Maika Monroe Tău (Negură Bunget album), a 2015 album by Romanian black metal band Negură Bunget Tau, an alien race from Warhammer 40,000 Tau, a character in the Battle Arena Toshinden fighting game series Pan Tau, hero of Czech films and television series Tau Zero, a novel by Poul Anderson Tau Volantis, a planet shown in Dead Space 3 Tau Cannon, an energy weapon from the video game Half-Life Tau Films, an American visual effects and animation company Colony Tau, a location from Xenoblade Chronicles 3 Education Tama Art University Tel Aviv University Texila American University Anna University of Technology, Tiruchirappalli People Abel Tau, South African politician Jimmy Tau, South African football (soccer) player Max Tau, German-Norwegian writer, editor, and publisher Nicolae Țâu, Moldovan politician who was Foreign Minister of Moldova between 1990 and 1993 Parks Tau, South African politician who was mayor of Johannesburg from 2011-2016 Tau (rapper), Polish rapper Devi Lal (politician), Indian politician who was Deputy Prime Minister from 1989 to 1991 Other Tau (mythology), an evil spirit in Guaraní mythology Tau effect, a sensory illusion relating to the perception of space