The experimental fiber-optic spectrograph FLEX being developed for the 4.2-m William Herschel Telescope (WHT) at Tenerife is briefly described and illustrated with a drawing. FLEX is designed to serve as an interim general-purpose spectrograph on the WHT before ISIS becomes operational and as a testbed for future instruments. Essentially, the UNIT spectrograph of the Isaac Newton Telescope was modified by adding new collimation and guiding systems, adapting it for CCD and IPSC detectors, and making the camera optics focus far enough from the structure to permit enclosure of the detectors in a cryostat. For trials of multiobject spectroscopy, the standard 400-micron fiber bundles used at the AAT were employed. Potential applications include (1) measurements of the internal velocity distribution of early-type galaxies in nearby rich clusters of galaxies and (2) two-dimensional spectroscopy of the circumnuclear regions of active galaxies.