The Dunkelgrafen (French : Comte et Comtesse des Ténèbres) - « Dark Counts » in German - is the nickname given by the locals to a wealthy couple who lived in the vicinity of Hildburghausen, Thuringia in the early 19th century.
The Dunkelgrafen arrived in Hildburghausen on 7 February 1807. In 1810 they moved into the nearby, but secluded castle of Eishausen where they stayed until their deaths. The man presented himself as Count Vavel de Versay and kept the woman’s identity secret, making only clear that they were neither married or lovers. They led a secretive life, particularly the Countess who ventured out only in a carriage or with a veil covering her face. At her death (November 28, 1837) she was inhumed very fast, possibly without a religious service. The Count - later identified as Leonardus Cornelius van der Valck (born 22 September 1769 in Amsterdam), secretary in the Dutch embassy in Paris from July 1798 to April 1799 - gave her name as Sophie Botta, single woman from Westphalia ; according to Dr Lommler, the physician who constated her death, she looked about 60 years of age. She was buried in a grave on Schulersberg hill, in a garden that the Dunkelgrafen had bought in 1820. The Count stayed in the castle and died there in April 8, 1845. He was buried in the churchyard of Eishausen. The castle in which the Dunkelgrafen had lived was demolished in 1873.
The mysterious couple sparked much interest and speculations about the identity of the Countess started early on. The most notable – with very few support from historians though – proposes that she would be the true Marie-Thérèse, daughter of Marie Antoinette, imprisoned in the Temple and supposedly redeemed in 1795 in exchange for French prisoners. According to this hypothesis, Marie-Thérèse, traumatized by her trials or pregnant by rape, would have refused to go back in the world ; her half sister, Ernestine Lambriquet, would have taken her place.
The Dunkelgrafen are the theme of numerous historical essays and fictions in German and French, among them a novel by Ludwig Bechstein.
On 15 October 2013 the remains of the Dunkelgräfin were exhumed for DNA tests. She was solemnly reburied on 7 November 2013. DNA analysis and a study of her reconstructed facial features clearly confirmed that she was not related to Marie Antoinette.
- Belcroix, Cyr (1999). Autour de Louis XVII : la comtesse des ténèbres. La Chapelle-la-Reine: le Relais. ISBN 978-2902693481.
- Richard Boehmker: Das Geheimnis um eine Königstochter. Die Lösung des mehr als 100jährigen Rätsels von Hildburghausen. Helingsche VA, Leipzig 1937
- Siebert, A. E. Brachvogel. Neu hrsg. von Theodor (1990). Das Rätsel von Hildburghausen : Roman (Reprint der Ausg. Berlin, Globus-Verl.,  ed.). Hildburghausen: Verl. Frankenschwelle. ISBN 3-86180-015-2.
- Lilienstern, Helga Rühle v. (1997). Dunkelgraf und Dunkelgräfin im Spiegel von Zeugen und Mitwissern (1. Aufl. ed.). Hildburghausen: Verl. Frankenschwelle. ISBN 3861800675.
- Lilienstern, Helga Rühle v. (2003). Die Unbekannten von Eishausen : Dunkelgraf und Dunkelgräfin im Spiegel zeitgenössischer Veröffentlichungen (4. Aufl. ed.). Hildburghausen: Verl. Frankenschwelle. ISBN 386180056X.
- Salier, Helga Rühle von Lilienstern ; Hans-Jürgen (2008). Das grosse Geheimnis von Hildburghausen auf den Spuren der Dunkelgräfin (1. Aufl. ed.). Leipzig: Salier. ISBN 978-3-939611-19-6.
- Lannoy, Mark de (2007). Das Geheimnis des Dunkelgrafen : war Prinzessin Marie Thérèse Charlotte de Bourbon seine Begleiterin?. Norderstedt: Books on Demand. ISBN 978-3833468476.
- "Was Germany's 'Dark Countess' the daughter of executed French royals Louis XVI and Marie Antoinette? Mystery could be solved after grave is exhumed". Daily Mail. 13 November 2014.
- "Dunkelgraefin war keine Prinzessin und nicht Tochter von Ludwig XVI". Spiegel. 29 July 2014.