Idris is a discontinued multi-tasking, Unix-like, multi-user, real-time operating system released by Whitesmiths, of Westford, Massachusetts.

In 1986, David M. Stanhope at Computer Tools International ported Idris to the Atari ST[1] and developed its ROM boot cartridge.

A specific version of Idris (CoIdris) was packaged as a .COM file under DOS and used it for low level I/O services.

Idris was ported to the Apple Macintosh (as MacIdris) by John O'Brien (of Whitesmiths Australia) and remained available until the early 1990s.

[2] After Whitesmiths had been merged with Intermetrics, Idris – along with its development toolchain – was ported by Real Time Systems Ltd to the INMOS T800 transputer architecture for the Parsytec SN1000 multiprocessor.