This is a list of operating systems for computers.

The first operating systems

The first proprietary computer operating systems

Unix-like and other POSIX-ready systems

Generic/commodity, non-UNIX, and other

Hobby OS

Operating systems written for a hobby.

Proprietary

Acorn

Amiga

Atari ST

Apple

Be Incorporated

Digital/Compaq/HP

IBM

Microsoft

Personal digital assistants (PDAs)

Microcontroller, embedded

Little operating systems that run on small devices.

Fictional operating systems

Operating systems that have only appeared in fiction or as jokes.