The Windows 11 Topic by 9gr
The original 9gr-based topic focusing on 10 & 11, created at 11's announcement. It's one of the biggest Advanced Topics to date!

The Windows XP/Vista/7 Topic by SuperSonicmario
The first one created for the December 2025 topic expansion. It focuses on the 2000s era of Windows, considered one of the most memorable.

The Windows 95/98/ME/2000 Topic by medians
Also from the December expansion, it focuses on the beginning of the home PC era, the Internet's expansion, and everything going on with Windows during that time.

The Windows 1.x/2.x/3.x Topic by medians
The third one from the same expansion is about the beginning of Windows, from its early development to the creation of NT.

The Windows 8/8.1 Topic by ma007rio
The fourth expansion topic is for discussion about one of the most hated versions of Windows: 8 (including the 8.1 update).

The Windows Phone 7/8/8.1/Windows 10 Mobile Topic by gem1001
A topic applicable to all Windows Phone (later Mobile with Windows 10) versions, known for their failures.

(main link) The MacOS Topics by 2016s4m29
Although not about Windows, they're for its main rival ever since they were both created: Apple's macOS.
(specific ones by medians and mtnif)
Classic Mac OS/Rhapsody topic
OS X/Mac OS X Topic (10.0 to 10.9)
MacOS/OS X (10.10 to 10.15)
macOS 11.0 and up topic

The Ubuntu Topic by StudioPangoFan_2000
Discuss the Debian-based and most popular Linux distribution developed by Canonical!

Series 30/Symbian/Asha Topic by gem1001
Chat about older mobile OSes, often nostalgic, right here!

The gOS Topic by kip22s
Ever heard about an early web-powered OS with Google services, but an Ubuntu fork?

The Windows 10 Topic by BabyBellaBoor
A companion to the Windows 11 Topic - but about its more popular predecessor, Windows 10 - and its legacy.

The Windows Beta Versions Discussion by abcde26
Talk about prerelease Windows builds and prototypes here!

Online OS Simulators Topic by gem1001
Explore and discuss the large variety of websites designed like OSes!

iOS/iPadOS/MacOS/tvOS/visionOS/watchOS 26 topic by romanoodles100

Linux by chocolatepenguin

The Virtual Machine Discussion by ScodexPerson

The Hackintosh/macOS VM Topic by StudioPangoFan_2000

2016s4m29 wrote:

New MacOS topic (not sure should this be added as a subsection or not.)

gem1001 wrote:

Should mobile versions of Windows be discussed on the topics for their main versions (e.g. Pocket PC 2000 on the 95/98/ME/2000 topic, Mobile 6.5/Phone 7 on the XP/Vista/7 topic, and Phone 8/8.1 on the 8/8.1 topic), or should there be a separate Windows CE/Pocket PC/Smartphone 2002/Mobile/Phone/10 Mobile topic or even separate Windows CE/Pocket PC/Smartphone 2002, Windows Mobile, and Windows Phone/10Mobile topics?

2016s4m29 wrote:

New MacOS topic (not sure should this be added as a subsection or not.)

gem1001 wrote:

I went ahead and made The Windows Phone 7/8/8.1/Windows 10 Mobile Topic

gem1001 wrote:

This should be called The OS Topic Directory at this point

kip22s wrote:

Browsers…

BabyBellaBoor wrote:

Windows 10 topic: https://scratch.mit.edu/discuss/topic/860856/