In Egyptian mythology, Isis is the goddess of fertility. She is also a guardian of the dead, and she allegedly has powerful magical abilities, including the ability to heal people. Historically, the goddess was often associated with the moon, which sometimes appeared in representations of her, typically held in a headdress that also included the horns of a cow.
According to legend, Isis was mortal once, but she tricked the sun god Ra into giving her some of his powers. She is also described as the sister to Osiris, as well as his wife. The name “Isis” means “Queen of the throne,” linking her with Osiris in his role as ruler, and in some representations, she wears an empty throne as a headdress, symbolizing the severed link between herself and Osiris.
The most well-known tale about Isis involves the death and resurrection of Osiris. According to legend, Osiris was murdered by his brother Set, and brought back to life by Isis so that the two could have a son, Horus. Horus was hidden until adulthood so that he could take revenge on Set, while Osiris was torn apart by Set in a fit of rage. Although the goddess was able to reassemble her husband and bring him back to life again, he was officially considered dead, and sent to the underworld.
Many statues of Isis show her suckling or holding the infant Horus, reinforcing her role as a goddess of fertility, and in some regions she was worshiped as a goddess of childbirth as well. In addition to being the goddess of fertility, she was also one of the goddesses who looked after the dead, tending to the canopic jar that holds the liver, and she was viewed more generally as a goddess of protection and defense because she watched over the dead.
In addition to being venerated in Egypt, Isis was also a figure of worship in Greece and Rome. Isis cults made their way to Greece around the third century BCE, and reached Rome not long afterwards. These cults often acted out the story of Isis and Osiris annually, as a symbol of rebirth and fertility, and by all accounts, their rites were quite raucous. Worship endured through the sixth century CE, although such cults had largely been stamped out by then.
Some people have suggested that the story of Isis has some links with the story of Mary and Christ in Christianity, and it is possible that early Christians were influenced by the myths. Certainly, both are mother figures, and some forced converts may have found comfort in viewing Mary as a version of Isis.