Ground Cover Succulents
This is a short list on purpose. A succulent that genuinely works as ground cover has to stay low, spread sideways rather than upward, and close ranks fast enough to shade out weeds. Most of the nursery is rosette or trunk forming and does not do that, so rather than pad the page we have kept it to the plants that actually mat or trail.
Ground cover succulents pair well with decomposed granite or a fine gravel, which holds the soil in place while the plants fill in and keeps the stems off wet ground. Spacing is the decision that matters: check the mature width and plant at roughly two thirds of it if you want closure in two seasons. On a slope, read the erosion control plants page as well, since spread and root binding are different jobs.