Shisa (シーサー Shīsā?, Okinawan: shiisaa) is a traditional Ryukyuan decoration, often in pairs, resembling a cross between a lion and a dog, from Okinawan mythology. People place pairs of shisa on their rooftops or flanking the gates to their houses. Shisa are wards, believed to protect from some evils. When in pairs, the left shisa traditionally has a closed mouth, the right one an open mouth. The open mouth wards off evil spirits, and the closed mouth keeps good spirits in.

From the Edo period, they started to be called "guardian dogs" in general in mainland Japan. Gender is variously assigned to the shisa. Some Okinawans believe the male has his mouth closed to keep bad out of the home, while the female has her mouth open to share goodness. Others believe the female has her mouth closed to "keep in the good", while the male has his mouth open to "scare away the bad". (Compare this to the distinction between male and female guardian lions in Chinese culture.)

Like the komainu ("lion dogs"), the shisa are a variation of the guardian lions ("fu dogs") from China. The shisaa, or lion dog, is an Okinawan cultural artifact. In magic typology, they might also be classified as gargoyle beasts. They are traditionally used to ward off evil spirits.