Boris III of Bulgaria
Princess Maria Luisa of Bourbon-Parma (Marie Louise Pia Theresa Anna Ferdinanda Francisca Antonia Margaret Josepha Carolina Blanche Lucia Apollonia; 17 January 1870 – 31 January 1899) was the eldest daughter of Robert I, the last reigning Duke of Parma. She became Princess-consort of Bulgaria upon her marriage to Ferdinand of Bulgaria, the then prince-regnant (who became Tsar after her death). She was the mother of Tsar Boris III of Bulgaria.