House Velaryon, a significant family in the prequel series House of the Dragon, was left out of the original Game of Thrones. Set 200 years before the events of Game of Thrones, House of the Dragon explores the history of House Velaryon and their role in the Targaryen dynasty. House Velaryon's wealth and influence come from their involvement in sea travel and their marriages to Targaryens. 

However, by the end of the Targaryen civil war, most of the notable members of House Velaryon have died out. In the original series, House Velaryon is mentioned in the books but does not have any prominent characters. However, in future Game of Thrones spinoffs, such as the upcoming Sea Snake spinoff, the family's presence is expected to be explored further. House Velaryon's history in the books is limited but highlights their loyalty to Stannis Baratheon.