Apple Operating Systems

Apple computers
There was no OS for the Apple I.

Apple II

 * Apple DOS
 * Apple ProDOS
 * Apple GS/OS

Apple III

 * Apple SOS

Apple Lisa

 * Lisa OS
 * MacWorks XL

Classic Mac OS

 * System 1
 * System 2
 * System 3
 * System 4
 * System Software 5 – also marketed as System 5
 * System Software 6 – also marketed as System 6
 * System 7 – System 7.5.1 was the first to refer to itself as Mac OS, Mac OS 7.6 was the first to be branded as "Mac OS"
 * Mac OS 8
 * Mac OS 9 – Mac OS 9.2.2 was the last version of Classic Mac OS

macOS
macOS was previously known as Mac OS X and later OS X.
 * Mac OS X Public Beta – code name Kodiak
 * Mac OS X 10.0 – code name Cheetah
 * Mac OS X 10.1 – code name Puma
 * Mac OS X 10.2 – also marketed as Jaguar
 * Mac OS X Panther – 10.3
 * Mac OS X Tiger – 10.4
 * Mac OS X Leopard – 10.5
 * Mac OS X Snow Leopard – 10.6
 * Mac OS X Lion – 10.7 – also marketed as OS X Lion
 * OS X Mountain Lion – 10.8
 * OS X Mavericks – 10.9
 * OS X Yosemite – 10.10
 * OS X El Capitan – 10.11
 * macOS Sierra – 10.12
 * macOS High Sierra – 10.13

macOS Server
macOS Server was previously known as Mac OS X Server and later OS X Server. Starting with Lion, there is no separate Mac OS X Server operating system. Instead the server components are a separate download from the Mac App Store.
 * Mac OS X Server 1.0 – code name Hera, also referred to as Rhapsody
 * Mac OS X Server 10.0 – code name Cheetah
 * Mac OS X Server 10.1 – code name Puma
 * Mac OS X Server 10.2 – code name Jaguar
 * Mac OS X Server 10.3 – code name Panther
 * Mac OS X Server 10.4 – code name Tiger
 * Mac OS X Server 10.5 – also marketed as Leopard Server
 * Mac OS X Server 10.6 – also marketed as Snow Leopard Server
 * Mac OS X Lion Server – 10.7 – also marketed as OS X Lion Server
 * OS X Mountain Lion Server – 10.8 – also marketed as Mountain Lion Server
 * OS X Mavericks Server – 10.9 – also marketed as Mavericks Server
 * OS X Yosemite Server – 10.10 – also marketed as Yosemite Server 4.0
 * OS X 10.11 Server 5.0 – also marketed as OS X Server 5.0
 * OS X 10.11 Server 5.1 – also marketed as OS X Server 5.1
 * macOS 10.12 Server 5.2 – also marketed as macOS Server 5.2
 * macOS 10.12 Server 5.3 – also marketed as macOS Server 5.3
 * macOS 10.13 Server 5.4 – also marketed as macOS Server 5.4
 * macOS 10.13 Server 5.5 – also marketed as macOS Server 5.5

Other macOS-related releases

 * NeXTSTEP
 * OpenStep
 * Darwin

Others

 * A/ROSE
 * A/UX
 * AIX for Apple Network Servers
 * Macintosh Application Environment
 * MkLinux
 * PowerOpen Environment
 * Star Trek – unreleased
 * Taligent – unreleased
 * Copland – unreleased

Newton

 * Newton OS

iPod

 * iPod OS

Apple TV Software
There was no Apple TV Software 8, version 8 was skipped when moving to tvOS.
 * Apple TV Software 1 – derived from Mac OS X 10.4 Tiger
 * Apple TV Software 2 – derived from Mac OS X 10.4 Tiger
 * Apple TV Software 3 – derived from Mac OS X 10.4 Tiger
 * Apple TV Software 4 – derived from iOS 4 and iOS 5
 * Apple TV Software 5 – derived from iOS 5 and iOS 6
 * Apple TV Software 6 – derived from iOS 7
 * Apple TV Software 7 – derived from iOS 8

tvOS

 * tvOS 9 – derived from iOS 9
 * tvOS 10 – derived from iOS 10
 * tvOS 11 – derived from iOS 11

iOS
iOS was previously known as iPhone OS, despite also being available on the iPod Touch (1st, 2nd, and 3rd generations) and the original iPad.
 * iPhone OS 1 – derived from "OS X" (At the time, "macOS" was still known as "Mac OS X" and not "OS X" as it was known from 2012 to 2016.)
 * iPhone OS 2
 * iPhone OS 3
 * iOS 4 – continued from iPhone OS 3
 * iOS 5
 * iOS 6
 * iOS 7
 * iOS 8
 * iOS 9
 * iOS 10
 * iOS 11

watchOS

 * watchOS 1 – derived from iOS 8
 * watchOS 2 – derived from iOS 9
 * watchOS 3 – derived from iOS 10
 * watchOS 4 – derived from iOS 11

audioOS

 * audioOS 11 - derived from iOS 11