G3 may refer to:

• PowerPC G3 - a microprocessor branding used by Apple Computer
  • iMac G3
  • PowerBook G3
  • Power Macintosh G3
• a group of three industrialized nations consisting of Japan, the United States and Germany
• Canon PowerShot G3 – a digital camera made by Canon
• G3 Free Trade Agreement
• a live music show tour featuring guitarists Steve Vai, John Petrucci, Joe Satriani, Eric Johnson, Yngwie Malmsteen and Billy Sheehan, among many others
• Heckler und Koch G3 – an assault rifle
• a line of boats from Yamaha
• G3 star, a subclass of G-class stars
• Group 3 of the periodic table

See also

• G4
• G5