Twm

English: twm (Tom's Window Manager or Tab Window Manager) is the standard window manager for the X Window System.

[edit] Screenshots

Twm with a lot of applications	With mainly terminal applications	Showing iconified windows	xterm
The twm main menu	Twm with	A comparisation of different window managers	The twm to example xkill...
...and after killing	A testing program with a hole.	A screenshot of Xnest