Graphical environment through which a user interacts with data and applications on a computer. Most of those listed below are avaiable as open-source software (OSS).

• 3Dsia Virtual Reality Shell
• The STOA Consortium - see Berlin Declaration on Open Access
• Common Desktop Environment (CDE) - proprietary
• DirectFB - thin library that provides hardware graphics acceleration, input device handling and abstraction, integrated windowing system with support for translucent windows and multiple display layers on top of the Linux Framebuffer Device
• Enlightnment - window manager for X Windows
• FVWM (Fill_in_the_blank_with_whatever_f_word_you_like_at_the_time
Virtual Window Manager) - ICCCM-compliant multiple virtual desktop window manager for X11
• General Graphics Interface (GGI)
• GNOME
• Mass Interactive Desktop for Linux
• Ion - a text-editorish, keyboard friendly X11 window manager (based on PWM)
• K Desktop Environment (KDE)
• KDE 2.0 Development - online book
• KDE.News - KDE announces launch of KDE Leauge, group of industry leaders and KDE developers focused on facilitating the promotion, distribution, and development of KDE
• Motif - proprietary
• OPaC - class library for building a portable GUI toolkit
• OpenLook
• PWM - lightweight window manager for X11 with the unique feature that multiple client windows can be attached to the same frame
• sawfish - extensible window manager using a Lisp-based scripting language
• Three-Dimensional Window Manager (3DWM)
• Unix Desktop Environment (UDE) Project
• Window Maker - X11 window manager designed to give additional integration support for GNUstep applications, while emulating the elegant look and feel of the NeXTSTEP GUI
• XFce - lightweight desktop environment for various UNIX systems
• X Windows