Wiktionary
n. One who has assassinated a member of a royal family.
Wikipedia
Royal Assassin is a book by Robin Hobb, the second in her Farseer Trilogy. It was published in 1996.
Usage examples of "royal assassin".
There was irony in my queen offering to protect the royal assassin.
Long before I had arrived, Chade had been the royal assassin, bearing the King's Justice in the form of quiet work wherever it neededto go.
There had been a time when Lord Chade was a hidden resident of Buckkeep Castle, the royal assassin only, a man who concealed his pocked face and carried out the King’.
There had been a time when Lord Chade was a hidden resident of Buckkeep Castle, the royal assassin only, a man who concealed his pocked face and carried out the King's justice in the shadows.