Sandy is a diminutive of Sandra, or Alexandra. Sandra originates in Greek language and means "protector of humanity". Most likely, it is a diminutive of the name Alexandra, possibly Cassandra. In the U.S., it was very popular in the 1950s. Alexandra is a feminine form of Alexander. Saint Alexandra was a martyr of the Diocletianic persecutions. Throughout history, there have been many members of royalty given the name Alexandra. In Greek mythology, Alexandra was a by-name of the goddess Hera. The name was popularized by Alexander the Great.