Sag or SAG may refer to:
- sag (geology)
- a sag pond
- a lens sag, distortion of astronomical lenses and mirrors
- Sag wagon in bicycling
- Sagittarius (constellation), in astronomy
- Sagittarius (astrology)
- Sag Harbor, New York
- Sâg, a commune in Sălaj County, Romania
- Şag, a commune in Timiş County, Romania
- Screen Actors Guild (SAG)
- Screen Actors Guild Awards
- Temporary or long term reduction of an electrical grid voltage, a brownout (electricity)
- Saag, a spinach and/or mustard leaf curry dish eaten in India and Pakistan
- Semi-Autogenous Grinding, a technique used in milling (see Mill (grinding)#SAG mill)
- SQL Access Group
- Saudi Arabian Government
- South Asian Gate, to be Kunming's largest building
- SAg, short for superantigen
- State Attorney General
- Surface Action Group
- Sango language ISO 639 code
- Dog (Persian translation)
- Student Assessment Guide
- SAG S-Arrestin, gene for a human protein involved in vision