Early Systems

From Applepedia

System 1 

First release of the MacOS

System 2.1 

MacOS starts using HFS instead of MFS

System 3.0 

SCSI and AppleTalk support

System 5.0 

Color QuickDraw, and the MultiFinder (a glimpse of how the classic MacOS would work like 'till the end of its days)

List of Mac OS versions

Classic Mac OS: System 1-5, System 6, System 7, Mac OS 8, Mac OS 9

Mac OS X: Mac OS X 10.0 (Cheetah), Mac OS X 10.1 (Puma), Mac OS X 10.2 (Jaguar), Mac OS X 10.3 (Panther), Mac OS X 10.4 (Tiger), Mac OS X 10.5 (Leopard)