| Qimo 4 Kids | — | — | GNU General Public License |
| QtMoko | — | — | — |
| Quantian | Dirk Eddelbuettel | — | GNU General Public License |
| Qubes OS | — | — | GNU General Public License, version 2.0 |
| RancherOS | Rancher Labs | — | Apache Software License 2.0 |
| Raspberry Pi OS | Raspberry Pi Holdings | 2012 | GNU General Public License |
| Raspbian | — | — | — |
| RebornOS | — | — | — |
| Recalbox | — | — | PRS Custom |
| Red Flag Linux | — | — | — |
| Red Hat Enterprise Linux | Red Hat | 2002 | — |
| Red Hat Linux | Red Hat | 1994 | GNU General Public License |
| RED OS | — | — | commercial software |
| Red Star OS | Korea Computer Center | — | — |
| Redcore Linux | — | — | — |
| RedHawk Linux | — | — | — |
| Refracta | — | — | GNU General Public License, version 2.0 |
| Regata OS | — | — | — |
| Remix OS | — | — | — |
| RetroPie | — | — | GNU General Public License |
| Rhino Linux | — | — | — |
| Rocks Cluster Distribution | San Diego, University of California, San Diego Supercomputer Center | — | — |
| Rockstor | — | — | — |
| Rocky Linux | Rocky Enterprise Software Foundation | — | 3-clause BSD License |
| Roku OS | Roku, Inc. | 2004 | — |
| ROSA Linux | LLC "STC IT ROSA" | 2011 | GNU General Public License, version 2.0 |
| RouterOS | MikroTik | — | — |
| RubyFPV | — | — | — |
| Runtu | — | — | — |
| Sabayon Linux | — | — | GNU General Public License |
| Sabily | — | — | GNU General Public License |
| Sailfish OS | Jolla | — | — |
| Salix OS | — | — | GNU General Public License, version 3.0, GNU General Public License, version 2.0, Creative Commons Attribution-ShareAlike 3.0 Unported, BSD licenses |
| SambaEdu | — | — | GNU General Public License |
| SAMity Linux | — | — | — |
| Satux | — | — | — |
| Scientific Linux | Fermilab | — | GNU General Public License |
| SCore | RWCP | — | — |
| Secureblue | — | — | Apache Software License 2.0 |
| Security Onion | — | — | — |
| Seminarix | — | — | — |
| Serbian GNU/Linux | — | — | — |
| Shinux | — | — | free software license |
| SHR | — | — | GNU General Public License |
| ShredOS | — | — | GNU General Public License, version 2.0 |
| Siduction | — | 2011 | GNU General Public License |
| SimpleLinux | — | — | — |
| Slackware | Patrick Volkerding | — | GNU General Public License |