Katrina Law (born Joyce Houseknecht) is an American actress. She is known for playing the roles of Mira on the Starz television series Spartacus: Blood and Sand and Spartacus: Vengeance, Nyssa al Ghul on The CW television series Arrow, Karen Beach on the Sony Crackle series The Oath, Quinn Liu on the CBS series Hawaii Five-0, and Jessica Knight on the CBS series NCIS. (Via Wikipedia)