(CBR) "Game of Thrones" fans are already well acquainted with House Tyrell. The dashing young knight Loras was part of the series from the very beginning, followed shortly by his game-playing queen-to-be sister Margaery in Season 2. In the third season of the hit HBO drama, their grandmother, the Queen of Thorns, made her arrival.

Now, with Season 4 on the horizon, one more thorn is joining the garden.

"A Song of Ice and Fire" author George R.R. Martin revealed on his blog that British actor Roger Ashton-Griffiths will play Mace Tyrell, the son of the Queen of Thorns and the father of Loras and Margaery. In the novels, he’s an integral player in the politics of Westeros and the game of thrones playing out in King’s Landing. It appears that showrunners David Benioff and D.B. Weiss felt the character was important enough to include in their adaptation.

Ashton-Griffiths is just the latest name to sign on for "Thrones‘" fourth season. Also joining the fray are Chilean actor Pedro Pascal as Prince Oberyn Martell of Dorne, "Rome" and "Human Target" actress Indira Varma as Oberyn’s lover Ellaria Sand, and "Sherlock" actor and co-creator Mark Gatiss in an unspecified role.

Ironically, many believed Gattis was aboard as Mace Tyrell. Now, the guessing game surrounding his character is suddenly a whole lot more interesting.

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