Solaris

Solaris (originally called SunOS) is a high-end workstation and server operating system developed by Oracle (formerly Sun Microsystems, Inc. who were bought out by Oracle in 2010). Solaris had many desktop environments. Suntools, was introduced in the mid-1980s for Sun's own Sun-3 workstation. When Solaris 2.0 was released, they started using OpenWindows, then CDE, and then (as now) GNOME.

In 2005, OpenSolaris was released by Sun. When Oracle acquired Solaris, it was announced that OpenSolaris would be discontinued and Solaris 11 would be released under a proprietary license. It's successor is Illumos which comes in various distributions such as OpenIndiana, SmartOS, Tribblix, and OmniOS.

Version list
Solaris / SunOS 5.x