A rumor going ground for a couple days now is that Asir Ahmad has been cast as Thoros of Myr.
Asim Ahmad has been in movies such as The Dark Knight, Inception and recently performed as a supporting character in the movie S.W.A.T.: Fire Fight. He has performed in the West End in the Lord of the Rings stage show as the role of Boromir. He has also performed with the RSC, playing roles such as Mercutio in Romero and Juliet, and Prospero in The Tempest.
There is no confirmation from HBO and sources are a bit vague and inconclusive.
The first is this comment from about a friend whose boyfriend got the job.
The second source being 2 tweets from Ahmad himself.
Assuming he met Emilia Clarke when picking up his scripts during the pre-production meetings at the end of June it could very well mean he is our Red Priest of Myr! His CV informs us he has sword fighting experience as well as stunt work experience and he has a good look for a Priest o Myr (albeit younger than I expected). Perhaps Asim Ahmad is going from playing Boromir to Thor'o'Myr....
For more casting rumors cheek this post here.
I update it regularly.