System 9

System 9 or System IX may refer to:

Computing

 * 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

 * STS-9 (Space Transportation System-9), the Space Shuttle mission