Windows 9 was the only one worth using.
All Windows branded as NT as well as 2000 (the first NT not branded as such) predate Windows 8 by over a decade, so I don't understand why you'd think one of them would be number 9.
Edit: Just realized GPs joke... There never was a Windows 9... And it isn't even that late...
Of course, that would leave out the consumer line starting with Win 95.