| G | Data chart (APPLAUSE) |
| G721 | Raw CCITT G.721 //$bit ADPCM data |
| G723 | Raw CCITT G.723 3 or 5bit ADPCM data |
| G8 | Raw Graphics (one byte per pixel) Plane III (PicLab) |
| GAL | Album (Corel Multimedia Manager) |
| GAM | Fax document (GammaFax) |
| GB | Emulator ROM image file (Nintendo GameBoy) |
| GBC | Color emulator ROM image file (Nintendo GameBoy) |
| GBL | Global file |
| GBM | Genie Backup Manager file |
| GC1 | Lisp source code (Golden Common Lisp 1.1) |
| GC3 | Lisp source code (Golden Common Lisp 1.1) |
| GCD | Generic (TM) CADD drawing (earlier versions) |
| GCP | Image processing file (Ground Control Point) |
| GDB | Database file (InterBase) |
| GDF | Dictionary file (GEOS) |
| GDM | Bells, whistles, and sound boards module |
| GED | Graphic Environment Document (drawing) |
| GEM | Vector graphics (Ventura Publisher) |
| GEN | Compiled template (dBase Application Generator) |
| GEO | Geode (Geoworks) |
| GetRight | Unfinished-Download (GetRight) |
| GFB | Compressed gif image (GIFBLAST) |
| GFI | Graphics Link presentation (Genigraphics) |
| GFT | Font (NeoPaint) |
| GFX | Genigraphics Graphics Link presentation |
| GHO | Symantec ghost image file |
| GHS | Symantec ghost segment file (automatically spanning files over 2 GB in size) |
| GIB | Chart (Graph-in-the-Box) |
| GID | Windows 95 global index (containing help status) |
| GIF | Bitmap (CompuServe) |
| GIM | Graphics Link presentation (Genigraphics) |
| GIW | Presentation (Graph-in-the-Box for Windows) |
| GIX | Graphics Link presentation (Genigraphics) |
| GKH | Ensoniq EPS family disk image |
| GKS | GripKey document (Gravis) |
| GL | Animation file (GRASP graphical System for Presentation) |
| GLB | Microsoft Exchange Server resynchronization file |
| GLB | Textured 3-D scene file format |
| GLM | Datafile (Glim) |
| GLS | Datafile (Across) |
| GLY | Glossary (Microsoft Word) |
| GMF | CGM Graphics (APPLAUSE) |
| GMP | Tile map (Geomorph) (SPX) |
| GMR | Graphical monitor record (Schlafhorst Automation) |
| GNA | Graphics Link presentation (Genigraphics) |
| GNO | Genealogy document file (Genopro) |
| GNT | Generated executable code (Micro Focus) |
| GNX | Graphics Link presentation (Genigraphics) |
| GOC | Goc sorce code (Geoworks) |
| GOH | Goc header (Geoworks) |
| GP | Geode parameter file (Geoworks Glue) |
| GP3 | Guitar Pro 3 file |
| GPH | Graph (Lotus 1-2-3/G) |
| GPK | Program package (Omnigo) |
| GPP | Graph paper application file (GraphPap) (Generates graph paper) |
| GPX | GPS eXchange Format file |
| GR2 | Screen driver (Microsoft Windows 3.x) |
| GRA | Datafile (SigmaPlot) |
| GRB | Shell Monitor (MS-DOS v5.0) |
| GRD | Image processing grid file (CHIPS) |
| GRF | Graph (Charisma Graph Plus) |
| GRM | VISUAL EPR Input Data for FIntGraf |
| GRP | Pictures group (PixBase) |
| GRY | Raw graphic (GREY) |
| GS1 | Presentation (GraphShow) |
| GSD | Vector graphic (Professional Draw) |
| GSM | Audio stream Raw 'byte aligned (GSM 6.10 audio stream) |
| GSP | Zip file (Gnuzip) (Allows for output to html) |
| GSW | Worksheet (GraphShow) |
| GT2 | Music module (Graoumftracker) (new) (MOD) |
| GTH | IBM Gatherer file |
| GTK | Music module (Graoumftracker) (old) (MOD) |
| GUP | Data (PopMail) |
| GVL | RCL Software Gravel (astronomy simulator) file |
| GVP | Google Video Pointer |
| GWI | Novell GroupWise file |
| GWP | Greetings WorkShop (now Microsoft Picture It) file |
| GWX | Graphics Link presentation (Genigraphics) |
| GWZ | Graphics Link presentation (Genigraphics) |
| GXL | Graphics library (Genus) |
| GZ | Compressed file (Unix gzip) |
