Project Athena
MIT's 1983 campus computing project, meant to put workstations in front of students, which shipped Kerberos, X and Zephyr to the rest of the world along the way.
MIT launched Athena in 1983 with DEC and IBM supplying money and hardware. The goal was educational: thousands of workstations from different vendors, where a student could log in anywhere and find the same home directory and the same software. Making that work on an open campus network required things that didn't exist yet, so the project built them — Kerberos for logins without cleartext passwords, Hesiod for name lookups, Zephyr for messaging, and the X window system.
Planned for five years, it was extended to 1991 and then folded into MIT's regular IT operations. The world quickly forgot the campus environment itself. The by-products, however, sit in every Active Directory domain and, until Wayland, in every Linux desktop.