The Targaryens ruled over Westeros for centuries. However, when fans were introduced to the Targaryen family in Game of Thrones, they were practically extinct. However, one surprise member of the Targaryen family is revealed to be Maester Aemon, the elderly Maester at the Night's Watch who Jon Snow looks up to for wisdom.
Source：https://www.cbr.com/every-targaryen-hotd-relation-to-maester-aemon/
