| .ACM | BioWare | Audio Files | Interplay Audio File | Fallout | Bethesda Softworks |
| .BIO | IBM | System Files | BIOS File | Bethesda Softworks Fallout 2 | Bethesda Softworks |
| .CKM | Bethesda Softworks | Developer Files | Creation Kit Macro | The Elder Scrolls V: Skyrim | Bethesda Softworks |
| .EGT | EagleGet | Uncommon Files | EagleGet Temporary File | The Elder Scrolls IV: Oblivion | Bethesda Softworks |
| .ESM | Bethesda Softworks | Game Files | Bethesda Softworks Master File | Bethesda Softworks TES Construction Set | Bethesda Softworks |
| .ESP | Bethesda Softworks | Game Files | Elder Scrolls Plugin File | Bethesda Softworks TES Construction Set | Bethesda Softworks |
| .ESS | Bethesda Softworks | Game Files | The Elder Scrolls Saved Game | Skyrim VR | Bethesda Softworks |
| .FOS | Bethesda Softworks | Game Files | Fallout 3 Saved Game | Fallout 3 | Bethesda Softworks |
| .FUZ | Bethesda Softworks | Audio Files | Bethesda Softworks Voice File | Unfuzer | Bethesda Softworks |
| .GCD | General CADD Products | CAD Files | Generic CADD Drawing File | Bethesda Softworks Fallout 2 | Bethesda Softworks |
| .HKX | Bethesda Softworks | Game Files | The Elder Scrolls V: Skyrim Animation | The Elder Scrolls V: Skyrim | Bethesda Softworks |
| .LIP | CELSYS | Raster Image Files | Clip Studio Paint File | Bethesda Softworks TES Construction Set | Bethesda Softworks |
| .MSG | Microsoft Corporation | Text Files | Saved Email Message | Fallout | Bethesda Softworks |
| .NAM | Aqua-3D | Data Files | Aqua3D Network File | Bethesda Softworks GECK | Bethesda Softworks |
| .OMOD | Bethesda Softworks | Game Files | Oblivion Mod Archive | The Elder Scrolls IV: Oblivion | Bethesda Softworks |
| .PSC | Bethesda Softworks | Developer Files | Papyrus Script | The Elder Scrolls V: Skyrim | Bethesda Softworks |
| .SAV | Nintendo | Game Files | Saved Game File | Fallout | Bethesda Softworks |
| .SDP | Oracle Corporation | Data Files | StarOffice Presentation File | Fallout 3 | Bethesda Softworks |
| .SVE | Simutrans Development Team | Game Files | Simutrans Saved Game | Bethesda Softworks Fallout 2 | Bethesda Softworks |
| .TRI | Singular Inversions | 3D Image Files | FaceGen Polygonal Model File | The Elder Scrolls IV: Oblivion | Bethesda Softworks |
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