Brendan Cowell is expected to appear in multiple episodes during Season 7, so his role is more than a cameo, too.
Brendan Cowell is an Australian actor most famous in the U.S. for a role on The Borgias, in which he played recurring character Mattai.
On Game of Thrones he’s set to play a character named Harrag the Ironborn.
If you are super familiar with all of the characters from George R.R. Martin’s works—and if you are, good for you–you probably have still never heard of Harrag before.