Who is The King in The House of Dragons?

[Herbert Playz]

The very first king we see during the opening in episode 1 is king Jaehaerys Targaryen, he is known as the old king(since the realm had a long period of peace and he had a long reign). Since he had no heirs he hela great council which determined that Viserys would be the next king.

Viserys is the king we see in the current timeline. He is the father of princess Rhaenyra and the brother of Daemon Targaryen.