Unix was created in the 1960s at Bell Laboratories in New Jersey.
Mac OS X, which based on BSD which is from Berkley, CA 1977. 😈
Richard Stallman created a set of programs and libraries called GUN in 1983, but also created the idea of Free Software which later gave inspiration to Open Software via the GNU licence.
Linux by a guy named Linux Torvalds in Finland 1991. 🐧
Both Android and iOS devices, like iPhones, are based on these systems.