Princess Claire of Luxembourg (born Claire Margareta Lademacher on 21 March 1985) is a German bioethics researcher currently pursuing a doctorate in the field of organ donation ethics at Pontifical Athenaeum Regina Apostolorum. She is married to Prince Felix, the second son of Grand Duke Henri of Luxembourg.

Claire was born on 21 March 1985 in Filderstadt, Germany. She is the second child of Gabriele and Hartmut Lademacher. Her father, founder of LHS Telekommunikation and owner of castles in Croatia and Saint-Tropez, began his career at IBM and amassed an estimated €600 million by investing in the software industry. Claire and her older brother, Felix, grew up in Usingen. At the age of 11, Lademacher moved with her family to Atlanta, and was enrolled in Atlanta International School. The family returned to Germany in 1999 and from then on, Lademacher attended Frankfurt International School, before enrolling in Collège Alpin International Beau Soleil in Switzerland. In 2003, she began studying international communication at the American University of Paris. She married Prince Félix, second in the line of succession to the throne of Luxembourg, on 17 September 2013, and then again in a religious ceremony on 21 September 2013.
Having obtained her undergraduate degree, Lademacher worked in publishing for Condé Nast Publications in New York City and Munich. While an employee of Condé Nast Publications, she made the decision to pursue a career in academic bioethics. She proceeded to obtain a master’s degree in bioethics at the Pontifical Athenaeum Regina Apostolorum, receiving it with the distinction summa cum laude. At the same time, she was working for the UNESCO Chair of Bioethics and Human Rights, concerning herself primarily with research, event coordination and communications. In 2012, Lademacher was in Rome, preparing a doctorate in the field of organ donation ethics at Regina Apostolorum. The subject of her dissertation is the bioethical evaluation of consent for organ donation. The dissertation focuses on the situations in Germany, Austria, and the United States. For several months in the fall of 2012, she was a visiting scholar at the Kennedy Institute of Ethics at Georgetown University.
In addition to her native German, Lademacher speaks English, French, and Italian.

Lademacher met Prince Félix while studying at Collège Alpin International Beau Soleil. The couple attended the wedding of Prince Félix’s cousin, Archduke Imre of Austria, in Washington, D.C., in September 2012. In October, they attended the wedding of his older brother Hereditary Grand Duke Guillaume and Countess Stéphanie de Lannoy, but were not allowed to sit together at the ceremony.
On 13 December, the grand ducal household confirmed that Lademacher was engaged to marry Prince Felix. Lademacher was presented to the press at the Château de Berg on 27 December. The civil wedding took place on 17 September 2013 in Königstein im Taunus, Germany, it being customary that weddings take place in the bride’s place of residence. A religious ceremony followed on 21 September at the Sainte Marie-Madeleine Basilica in Saint-Maximin-la-Sainte-Baume, France.
Upon her marriage, Claire became a Princess of Luxembourg with the style of Royal Highness. Since the wedding, the couple has been living in the south of France at the Château Les Crostes, a winery in Lorgues that has been owned by the Lademacher family for many years.
The couple’s first child, Princess Amalia of Nassau, was born on 15 June 2014 at the Grand Duchess Charlotte Maternity Hospital in Luxembourg.
On 4 July 2016, the granducal court announced that Princess Claire and Prince Felix are expecting their second child sometime in autumn 2016. On 28 November 2016 Princess Claire gave birth to her second child, a son, Prince Liam Henri Hartmut of Nassau at Beaulieu General Clinic in Geneva.