PonyOS is a hobby operating system for everypony.
PonyOS is derived from とあるOS and is released under the terms of the NCSA license. It contains third-party software under various other licenses which are described in the original sources where available.
The wallpaper that comes with PonyOS is by BlueDragonHans and is released under the terms of the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License (distribution in this form does not qualify as a derivative work).
Pony art used for icons by KiNcHeFF (Terminal icon, CC BY) and ZuTheSkunk (Julia Fractal icon and Draw icon, CC BY-NC-SA)