System 9 or System IX may refer to:
Computing
edit- IBM System z9, the mainframe line
- Plan 9 from Bell Labs, the operating system
- Mac OS 9, latest release of Classic Mac OS operating system
- OS-9, the Unix-like real time operating system
- SYSTEM POWER 9, line of power supplies by be quiet!
Other
edit- STS-9 (Space Transportation System-9), the Space Shuttle mission