The Macintosh SE/30 is a personal computer that was designed, manufactured and sold by Apple Computer, Inc. from 1989 until 1991. It was the fastest and most expandable of the original black-and-white compact Macintosh series.

The SE/30 is essentially a Macintosh IIx in the same case as the Macintosh SE, with a black-and-white monitor and a single PDS slot (rather than the NuBus slots of the IIx) which supported third-party accelerators, network cards, or a display adapter. Although officially only able to support 8 MiB, the SE/30 could expand up to 128 MiB of RAM, and included a 40 or 80 MB hard drive. It was also the first compact Mac to include a 1.44 MB high density floppy disk drive as standard (late versions of the SE had one, but earlier versions did not). Conversion sets were sold to convert a regular SE to a SE/30. The SE would then have the exact same specs as an SE/30, with the difference only in the floppy drive if the SE had a 800k drive. The set included a new front to replace the original SE front with that of an SE/30.

Apple had indicated the presence of a 68030 processor by adding the letter "x" to a model's name, but when the Macintosh SE was updated to the 68030, this posed an awkward problem, as Apple was not willing to name their new computer the "Macintosh SEx". Thus, "SE/30" was the name chosen. Internally, code names like Green Jade and Fafnir were used