| NanoQplus | Electronics and Telecommunications Research Institute | — | — |
| NASLite | — | — | — |
| Navigatrix | — | — | GNU General Public License |
| NCOS | Acorn Computers, Pace plc | — | — |
| NCR VRX | NCR Corporation | — | — |
| Nemesis | University of Cambridge | — | — |
| NeoKylin | — | — | proprietary license |
| NepaLinux | Madan Puraskar Pustakalaya | — | GNU General Public License |
| NetBSD | — | 1993 | BSD licenses |
| NetHunter | — | — | — |
| Netrunner | Blue Systems | — | GNU General Public License |
| NetSecL OS | — | — | GNU General Public License |
| NetWare | Novell | — | — |
| NewDos/80 | — | — | — |
| NewOS | Travis Geiselbrecht | — | — |
| Newton OS | Apple Inc. | — | — |
| Newtoos | — | — | — |
| Nexenta OS | Nexenta Systems | — | Common Development and Distribution License version 1.0 |
| NexentaStor | Nexenta Systems | — | — |
| NeXT Computer | — | 1988 | — |
| NextBSD | — | — | BSD licenses |
| NeXTSTEP | NeXT | — | proprietary license |
| NimbleX | — | — | — |
| Nintendo 3DS system software | Nintendo | — | — |
| Nintendo DSi system software | Nintendo | — | — |
| Nintendo IOS | Nintendo | — | — |
| Nintendo Switch system software | HAL Laboratory, Nintendo | 2017 | proprietary license |
| Nitix | — | — | — |
| Nitrux | Camilo Higuita | — | — |
| NixOS | Thomas Tuegel, Eelco Dolstra | — | MIT License |
| NLTSS | Lawrence Livermore National Laboratory | — | — |
| NND | — | — | — |
| Nobara (operating system) | Thomas Crider | — | — |
| NodeOS | — | — | MIT License |
| NOI Linux | — | — | — |
| Nokia Asha platform | Nokia, Microsoft Mobile | — | — |
| Nokia Fastlane | Nokia | — | — |
| Nokia X | — | — | — |
| NomadBSD | — | 2018 | 2-clause BSD License |
| NonStop OS | Tandem Computers | — | — |
| Nonux | — | — | GNU General Public License |
| NORD | — | — | — |
| NorthStar DOS | North Star Computers | — | — |
| NORTON-BK | — | — | — |
| NOS | Alien Internet Services | — | — |
| NOS | Control Data Corporation | — | — |
| NOS/VE | Control Data Corporation | — | — |
| Not Another Completely Heuristic Operating System | — | — | BSD licenses |
| Nothing OS | Nothing Technology Ltd. | — | Android Open Source Project |
| Nova | University of Information Science | 2014 | GNU General Public License |
| Novell S-Net | Novell | — | — |
| NUbuntu | — | — | — |
| Nucleus RTOS | Mentor Graphics | — | — |
| Nura | — | — | GNU General Public License, version 3.0 |
| Nut/OS | Ethernut | 2000 | BSD licenses |
| NuttX | Apache Software Foundation | — | Apache License, Apache Software License 2.0 |
| NuTyX | — | — | GNU General Public License |
| NVIDIA DGX OS | Nvidia | — | — |
| NX-OS | Cisco | — | — |
| Nyarch | — | — | — |