Clotilde, Countess von Merenberg (born 14 May 1941 in Wiesbaden, Germany) is a German psychiatrist and the last patrilineal descendant of the House of Nassau. She is a descendant of Emperor Alexander II of Russia and of the Russian poet Alexander Pushkin.

A psychiatrist, Clotilde is the only child of Count George von Merenberg (1897–1965) and Elisabeth Müller-Uri (1903-1963). She is the last patrilineal descendant of the House of Nassau, the male line of which ruled the Duchy of Nassau until 1866, provided a 12th-century German king, a line of Princes of Orange who served first as stadholders of the United Dutch Provinces and, from 1815 to 1948, as kings of the Netherlands, and reigned as grand dukes of Luxembourg until 1968. Neither she, however, nor her father or paternal grandfather were deemed full members of the Nassau dynasty, the last member of which, Grand Duchess Charlotte of Luxembourg, died in 1985.^[1] While Countess Clothilde's branch of the family had legitimate male members until 1965, they had been bypassed for Luxembourg's throne since 1907.

The Counts von Merenberg descend legitimately from the morganatic marriage in 1868 of Prince Nikolaus Wilhelm of Nassau and Natalia Alexandrovna Pushkina, a daughter of the renowned poet Alexander Pushkin, who was an untitled member of the lower Russian nobility. Although their son Count George von Merenberg married Princess Olga Alexandrovna Yurievskaya, a daughter of Tsar Alexander II of Russia, and pressed for recognition as heir presumptive to the Luxembourgeois throne as its grand ducal line approached extinction, a 1907 law of the grand duchy dismissed the Merenbergs' claim to the throne.

Prince Nikolaus was a great-grandson of Charles Christian, 3rd Prince of Nassau-Weilburg, who in 1760 married Princess Carolina of Orange-Nassau, a daughter of the Dutch stadholder William IV, Prince of Orange and Anne, Princess Royal of Great Britain. Countess Clotilde is also a great-granddaughter of the Russian Emperor Alexander II.