These are not strictly Unix, but either very similar or related in other way.
- Plan 9 from Bell Labs
Plan 9 started in Bell Labs in the mid 80s, as a research project where several new and interesting concepts
are explored. There were commercial releases in the 90s, but there was not much interest. Since 2002 it is
available as open source.
Link: Plan 9 Home Page at Bell Labs
- Inferno
Link: Inferno Home Page
- QNX
Link: QNX Home Page
- Apple's Mac OS X
- Mach Microkernel