Prince Trystane Martell is a recurring character in the fifth and sixth seasons. He is portrayed by Toby Sebastian and debuts in "The House of Black and White". Trystane is the eldest son and heir to Prince Doran Martell. He is betrothed to Myrcella Baratheon. He was murdered along with his father, Prince Doran, by Ellaria Sand and the Sand Snakes in an act of retaliation for his father's inaction against House Lannister for their crimes against House Martell.