WAndroid-x86
WArcaOS
WAROS Research Operating System
WAtheOS
WBeOS
WChrome OS
WChromium OS
WCoherent (operating system)
WCosmos (operating system)
WDragonFly BSD
WEComStation
WFirefox OS
WGenode
WGEOS (16-bit operating system)
WGhost (operating system)
WHaiku (operating system)
WHelenOS
WInferno (operating system)
WKolibriOS
WOpenIndiana
WOS/2
WPlan 9 from Bell Labs
WReactOS
WSerenityOS
WSkyOS
WSolaris (operating system)
WSyllable Desktop
WVxWorks
WXv6