Apple Star Trek
The Star Trek project was a partnership between Apple Computer and Novell to port Apple's System 7.1 operating system to the x86 platform. A working prototype was running on a 486 by late 1992 but the project was scrapped in 1993, though aspects of the project were likely reused in later products.
On the technical side, the base system was DR-DOS (Novell DOS) and the Macintosh system was essentially a GUI shell application. This hybrid concept would also appear in Apple UNIX (A/UX).