Haworthia cymbiformis
Native range: South Africa
Known names: Window succulent, Cathedral Window Succulent
Hardiness: Best kept above freezing
Mature Size: ~3" tall, cluster-forming
Light: Bright light, indirect sun, (direct sun can burn the plant)
Water: If possible, avoid much winter water, maybe once a month. Water more often during summer.
Soil: Fast draing, coarse succulent soil
Dormancy Period: N/A
Pet-Safe: Yes
Plant Size: Grown in 2.5" pot
 
Haworthia cymbiformis a fairly large form of the "window succulent". 
 
Haworthias, in the wild, generally grows underground with their "windows" poking up slightly to catch some sun. These succulents will actually do poorly if exposed to too much sun so it is best to grow them either with morning sun only or dappled sun or somewhere shaded away from the hot sun. 
Avoid overwatering in Summer; they'll end up rotting if the soil is wet and the weather is hot.