This is a list of different Unix variants, please do not add Linux distributions to the list, there should be a different list for those. The vast majority of the Unixes listed are from The operating systems catalog ^[1], from the Open Group, or from the Unix History files^[2]
Note most of these are not the part of official standard called Unix.
Contents: Top - 0–9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

0-9

A

• A/UX (Apple, 1986?)
• AMIX (Commodore, 1990's?)
• Atari Unix (1989)
• AIX (IBM)
• ACORN (ACORN)

B

• BSD

C

• Coherent (Mark Williams Corp, 1980's)
• Cromix - UNIX System V port for Cromemco (68000 CPU). Cromemco Corp., Late 1970

D

• Darwin (Apple, 1998?)
• DG\UX (Data General, 1985)
• DragonFly BSD
• Domain/OS - For Apollo computers, derived from BSD and Unix System V.

E

EP/IX

F

• FreeBSD

G

• Genix - UNIX version for the NSC 32016. National Semiconductor
• GNU (Richard Stallman)
• GNU Darwin

H

• HP-UX (Hewlett-Packard)

I

• IRIX (Silicon Graphics)
• IDRIS - Version of UNIX. 68000, 8086, PDP-11, VAX. (Whitesmiths, Ltd. Late 1970s)
• Inspur K-UX 2.0

J

L

• Linux (Linus Torvalds, 1993 first release, development on going, with many distributions.)

M

• Mac OS X
  • Mac OS X Server
• Minix
  • Minix 3

N

• NetBSD
• NeXTSTEP
• Nonstop-UX

O

• OpenBSD
• OpenDarwin
• OpenSTEP
• OpenSolaris (Sun

P

• Plan 9 from Bell Labs (Bell Labs)
• PC-UX (NEC)

Q

• QNX

R

• Research Unix
• RISC iX (Acorn, 1989)

S

• SCO OpenServer
• Sinix (1983)
• Solaris (Sun, 1980's)
  • SunOS (Sun, 1982 (becomes Solaris)

T

• Tru64 (DEC, Compaq, HP)

U

• Ultrix DEC PDP-11 and VAX. (DEC, Early 1980's)
• Unicos
• UniFLEX
• UNIX System V
• UnixWare

V

• Venix (1980)

W

X

• Xenix (Microsoft)

Y

Z

• Zeus - (Zilog Corp Late 1970s)

References