Mavis Vermillion is the first guild master and founder of Fairy Tail. She is also an analyst and strategist with the nickname "Fairy Tactician." Mavis dies at a young age years before the beginning of the series and is buried on Tenrou Island. After Cana Alberona pleads with her for help to protect her friends, Mavis's spirit grants Cana the Fairy Glitter spell. Her human form is revealed when the Fairy Tail members on the island are attacked by Acnologia. With Fairy Tail determined to protect each other, Mavis uses her Fairy Sphere spell to protect them. However, this inadvertently causes the island and his inhabitants to disappear from Earthland, freezing them in time. Seven years later, she appears in her human form and cheers for Fairy Tail while in Crocus, but can only be seen by those with the mark of Fairy Tail. She is also capable of sensing good or evil in a person.

Source from Wikipeida