ECW

• Extreme Championship Wrestling (originally Eastern Championship Wrestling), a professional wrestling promotion that operated from 1992 to 2001
• The Alliance (professional wrestling) (originally the WCW/ECW Alliance), a 2001 World Wrestling Federation stable that included Extreme Championship Wrestling
• ECW (WWE brand), a World Wrestling Entertainment brand from 2006 to 2010 based on the Extreme Championship Wrestling promotion

• ECW Hardcore TV, produced by the Extreme Championship Wrestling promotion from 1993 until 2000
• ECW on TNN, produced by the Extreme Championship Wrestling promotion from 1999 to 2000
• WWE ECW, produced by World Wrestling Entertainment from 2006 to 2010 based on the Extreme Championship Wrestling promotion

• Electronic counter-warfare, a set of military measures to counteract enemy radars, missile-guidance, etc.
• English Civil War(s), a series of armed conflicts and political machinations which occurred in England from 1642 to 1651

• Eastern Coach Works, a defunct bus body building company from England
• ECW (file format), an enhanced compressed wavelet file format designed for geospatial imagery
• ECW model in chemistry for Lewis acid–Lewis base interactions
• ECW Press, a Canadian book publisher
• Extreme Cold Warnings are issued to inform the public about active or imminent severe cold temperatures in their region that are expected to last for a while; examples:
• In the U.S., when temperatures fall to {{convert|-35|F}} or colder with winds of less than {{convert|5|mph|km/h m/s|abbr=on|0}}
• In Canada, based on either the temperature or the wind chill being a certain value for at least 2 hours; the values range from {{convert|-30|C}} in the warm temperates to {{Convert|-55|C}} in parts of the Arctic
• Extreme Cold Weather clothing for arctic or mountainous areas
• Extended Cold Weather Clothing System worn by members of the United States Army

{{Disambiguation}}