TRIPOS (TRIvial Portable Operating System) is a computer operating system. Development started in 1976 at the Computer Laboratory of Cambridge University and it was headed by Dr. Martin Richards. The first version appeared in January 1978 and it originally ran on a PDP-11. Later it was ported to the Computer Automation LSI4 and the Data General Nova. Work on a Motorola 68000 version started in 1981 at the University of Bath. MetaComCo acquired the rights to the 68000 version and continued development until TRIPOS was chosen by Commodore in March 1985 to form part of an operating system for their new Amiga computer; it was also used at Cambridge as part of the Cambridge Distributed Computing System.

Students in the Computer Science department at Cambridge affectionately refer to TRIPOS as the Terribly Reliable, Incredibly Portable Operating System. The name TRIPOS also refers to the Tripos system of undergraduate courses and examinations, which is unique to Cambridge University.