STAC may refer to:
Computers and electronics stac (Set AC Flag) instruction on x86 CPUs, part of Supervisor Mode Access Prevention Stac Electronics, a former American technology company Lempel–Ziv–Stac, a data compression algorithm developed by Stac Electronics SigmaTel Audio Codec an extended version of the Graphic Adventure Creator software SpatioTemporal Asset Catalog, an open specification to describe geospatial information.
Education Southern Theatre Arts Centre, a training venue in Durrington by Sea, Worthing, West Sussex, England St. Thomas Aquinas College, Sparkill, New York Saint Thomas Aquinas College (Sogod), Southern Leyte, Philippines St Andrew's College, Christchurch, New Zealand
Transportation Service des transports de l'agglomération chambérienne (Stac), a transport service in Chambéry, France; part of Compagnie générale française des transports et entreprises Service de transport adapté de la Capitale, a transport service in Quebec, Canada Special Transit Advisory Commission, a commission that founded the Triangle Transit transport service in North Carolina, United States STAC Swiss Government Flights, see List of airline codes (S) Supersonic Transport Aircraft Committee
Other uses STAC (protein), a protein containing a C1 domain Sepak Takraw Association of Canada, a sport association Sirtuin-activating compound, a class of biochemical compounds Spatial and Temporal Analysis of Crime, see Crime hotspots Stac, the Gaelic word for a sea stack, commonly used in Scotland
See also STACS