Isis is one of the main goddesses of the Egyptian pantheon. Among other things, she is the patron of magic.
The goddess Isis was introduced to the DC Universe in the 1970s TV series The Secrets of Isis. The show bookends the Shazam! TV series, which featured Captain Marvel. Isis was school teacher Andrea Thomas, who received the powers of the goddess Isis through a mystical amulet, by invoking "Oh Mighty Isis"; these words are also used by Zatanna to summon her.