Linux
Android-X86, ArchLinux, Debian, Fedora, Gentoo, Lineage, Mageia, Mklinux, OpenMadriva, Open-SUSE, Slackware, Ubuntu
Linux Beautiful Distributions
Cutefish, Deepin, Elementary, Garuda, Kylin, Manjaro, Mint, Nitrux, Orange π, Pop!_OS, Zorin
Linux for Education
AcademicX, Edubuntu, Epoptes, Opensis, openSUSE, Ubermix
Linux: Enterprise Servers
CentOS, Lineox, Red Hat, ScientificLinux, SUSE, Ubuntu
Linux for Old Hardware
Antix, Arch, Budgie, BunsenLabs, ChromeOS, DebianDog, Elementary, LXLE, Lite, Lubuntu, Porteus, PuppyLinux, Slitaz, Tyni Core, Xubuntu, Zorin Lite
Unix
AiryxOS, FreeBSD, FreesBIE, GhostBSD, HelloSystem, Illuos, MidnightBSD, NetBSD, OpenBSD, OpenIndiana
OTher OSes
Dahlia, DOSBox, ECos, FreeDos, Fuchsia, GNU Hurd, Minix3, ReactOS, Temple OS, Ubuntu Touch
Oldies
Macpaint, AranyM ATARI, AROS Amiga, Amikit, Aftershock, AtheOS, CDE; Commodore MAME, NsCDE, Vice, Z64k, DexOS,Haiku (BeOS)GoFish Gopher Server, KolibirOS, LUnix: Commodore64, MacOS9, MenuetOS, MorphOS (PPC), MS-DOS, OpenVMS, Stella Atari 2600, Windows95
OSUtils
Boot System, Fink, Hackintosh, Homebrew, OpenCore,
Open Source Licenses
Free and Non Free Software Copy-left, Noncopy-Left, & X11 Open Source Licenses The Free Software Foundation
Other Linux-Unix Issues
Distrowatch, MacOSForge, UnixGuide, GNU Hurd, Unix History, Commands, Cheat-Sheet The History of the Internet