The ENCOM OS-12, short for ENCOM Operating System 12.0, is a computer operating system released by ENCOM. Originally, it was to be called Flynn OS.

Designed by Edward Dillinger, Jr., OS-12 is the most secure operating system in the world. However, on the night it was meant to be put online for download and sale, Sam Flynn executed his yearly prank on the company by hacking ENCOM's servers and uploading the operating system online for free. At the same time, he replaced the program on ENCOM's website with a looped video of his dog.