Haworthiopsis fasciata or H. attenuata? Both these plants were recently (2013) moved from Haworthia to Haworthiopsis. They are sometimes commonly called zebra plants.
These plants are hardy South African leaf succulents that form clumps of rosettes and grow fairly easily in diverse, even harsh conditions. The Haworthiopsis genus is, like Haworthia, still part of the Asphodelaceae family.