'House of the Dragon' Lannister Family Tree: All About Twin Jason's House

House of the Dragon, like Game of Thrones before it, features a huge cast of characters, all of whom hail from their own respective ancient family line.

Characters in the HBO prequel are ancestors to many of Game of Thrones' fan favorites, and one such house of particular note is the Lannisters.

Names like Tyrion, Tywin, Jamie and Cersei will no doubt be familiar to fans of the original hit show, but House of the Dragon has added two more to that list: Jason and Tyland (both played by Jefferson Hall).

Here is everything you need to know about the characters and how they are related to the Lannister family of Game of Thrones.

House of the Dragon Lannister Family Tree: All About Twins Jason and Tyland's House

House of the Dragon
Main: Jefferson Hall as Lord Jason Lannister in "House of the Dragon." Inset: Peter Dinklage as Tyrion Lannister in "Game of Thrones." Jason Lannister is the great-great-great-grandfather to Tyrion and his siblings. Ollie Upton/Helen Sloan/HBO

Jason Lannister is lord of Casterly Rock at the time of House of the Dragon, with the show's third episode seeing him vie for Rhaenyra Targaryen's (Milly Alcock) hand in marriage.

The Lannister family have a long history in the region, as they were previously kings in their own right before Aegon Targaryen conquered Westeros.

As is explained in George R. R. Martin's books, particularly his book The World of Ice and Fire, during Aegon the Conqueror's rule Loren Lannister, known as "The Last," gave up his crown and became a lord.

Loren the Last continued to rule Casterly Rock but the family remained distant from the Targaryen family, only coming to their aid a generation later when Lord Lyman Lannister gave refuge to Prince Aegon and Princess Rhaena Targaryen from their father King Maegor the Cruel.

The Lannister family later came to support Prince Aegon and Princess Rhaena's brother Jaehaerys in his claim to the Iron Throne following Prince Aegon's death.

Tymond Lannister, the grandson of Lyman, was the Lord of Casterly Rock during the Great Council that decided who would take the Iron Throne following King Jaehaerys I. They threw their support behind Prince Viserys, who later was named the ruler's heir.

King Viserys I is Rhaenyra's father, and during his reign the Lannister family started to receive key roles in the realm, with Jason's twin brother Tyland being named his master of ships.

During the Dance of the Dragons, the civil war that broke out between the Targaryen family after King Viserys I's death, Lord Jason chose to support the late ruler's eldest son by Alicent Hightower (Emily Carey), Aegon Targaryen.

When Aegon was crowned king during this civil war Tyland became master of coin, while Lord Jason fought in battles for his regent until his death at the Battle at the Red Fork.

Lord Jason's son Loreon succeeded him, then Loreon's son Damon became Lord of Casterly Rock. Known as the Grey Lion, Damon is the great-grandfather of Tywin Lannister (played by Charles Dance in Game of Thrones).

This means that Jason Lannister is the great-great-great-grandfather of Tywin Lannister, and there are six generations between him and Tywin's children, Tyrion (Peter Dinklage), Jamie (Nikolaj Coster-Waldau) and Cersei (Lena Headey).

House of the Dragon airs Sundays on HBO and HBO Max.