| cdev | Macintosh II Control Panel |
| cdl | Maxon Cinema 4D Plugin |
| cdl64 | Maxon Cinema 4D 64-bit Plugin |
| cef | CenturionMail Encrypted Email |
| cgz | Linux Drivers Archive |
| chunk001 | File Splitter Split Archive Part 1 |
| cks | Windows CE ROM Image Checksum |
| clb | COM+ Catalog |
| clp | Windows Clipboard File |
| cm0012 | WD TV Live Corrupt Data |
| cmp | SimCreator Script |
| cng | C-NaviGator Software Update |
| cng3 | C-NaviGator Software Update |
| cn_ | Compressed Windows Help Content |
| component | Mac OS X System Component |
| con | OASIS Montaj Control File |
| conv | Stylus Studio Data User-defined Converter |
| cos2 | Pinnacle Studio Cache |
| cpq | Compaq OEM Disc Configuration |
| cpr | PV-WAVE Compiled Procedure |
| crc | CRC Checksum |
| crd | Microsoft Windows Cardfile |
| crdownload | Chrome Partially Downloaded File |
| crp | LG 2-3G Tool Firmware |
| crp1 | LG 2-3G Tool Firmware |
| crplugin | ComicRacks Plugin |
| crt | Certificate File |
| csr | Certificate Signing Request |
| csu | Crestron Software Update |
| cuj | Personal Backup Saved Task |
