Princess Elia was Prince Rhaegar Targaryen’s wife. The pair had a daughter and son. She and her children were killed during the Battle of the Trident at the hands of Gregor Clegane, the mountain. Elia was not shown in the TV series, however, it is revealed that Oberyn Martell came to Kings Landing in Season 4 to avenge her death. Elia was born into the House of Dorne and is the younger sister to Oberyn Martell and Prince Doran Martell.