The Macintosh SE was a personal computer manufactured by Apple. This computer marked a significant improvement on the Macintosh Plus design and was introduced by Apple at the same time as the Macintosh II. It had a similar case to the original Macintosh computer, but with slight differences in colour and styling.

Originally the SE could use only Single Density (SD) (400 KB) and Double Density (DD) (800 KB) formatted floppy disks. In August 1989, Apple introduced the Macintosh SE FDHD with the new SuperDrive, a floppy disk drive that could handle 1.4 MB High Density (HD) floppy disks. Some Macintosh SE FDHDs were labeled "Macintosh SE Superdrive" and are more rare. HD floppies would become the de-facto standard on both the Macintosh and PC computers from then on. In Europe, the Macintosh SE FDHD was renamed the Macintosh SE 1/20.

The SE was designed to accommodate either two floppy drives or a floppy drive and a hard drive, although an after-market bracket was designed to allow the SE to accommodate two floppy drives as well as a hard drive. After Apple introduced the Macintosh SE/30 in January 1989, an SE/30 motherboard was marketed as a high-cost upgrade for the SE.

Additionally the SE had a special PDS slot that allowed for expansion cards, such as accelerators, to be installed. Later on the SE/30 continued by having one slot. Still today accelerators can be purchased and installed in this machine. The SE can be upgraded to 50 MHz and more than 5 MB with the MicroMac accelerators, which are still sold. In the past other accelerators were also available such as the Sonnet Allegro.

The SE was discontinued in October 1990, with the introduction of the Macintosh Classic to succeed it. Apple produced ten SEs with transparent cases as prototypes for promotional shots and employees. They are extremely rare and command a premium price for collectors.