Doranbalt "Mest Gryder"

In X784, he used his Memory Control to deceive the members of the Fairy Tail into believing that he was a fellow guildmate named Mest Gryder for their S-Class Promotion Trial.

After the events of the Tartaros arc, Makarov told Doranbalt that he is a member of Fairy Tail guild all along. He erased his own memories in order to easily infiltrate the Magic Council. He also obtained back his guild insignia.