Guillaume V (Guillaume Jean Joseph Marie de Nassau; born 11 November 1981) is Grand Duke of Luxembourg, since 3 October 2025.

The eldest son of Grand Duke Henri and Grand Duchess Maria Teresa, he acceded to the throne upon the abdication of his father.

Early life and education

Guillaume was born on 11 November 1981 at the Grand Duchess Charlotte Maternity Hospital in Luxembourg City as the eldest child of Grand Duke Henri of Luxembourg and his wife, Cuban-born Grand Duchess Maria Teresa. His godparents are Princess Marie Astrid of Luxembourg and Prince Guillaume of Luxembourg. Guillaume has four younger siblings: Prince Félix, Prince Louis, Princess Alexandra and Prince Sébastien.

Guillaume attended public school, completing his primary education in Lorentzweiler and his secondary education at the Lycée Robert-Schuman in Luxembourg City, before attending Swiss boarding schools the Institut Le Rosey and the Collège Alpin International Beau Soleil where he finished the French baccalaureate in 2001; and Royal Military Academy Sandhurst, Camberley, England. In 2006 he entered Institut Philanthropos in Fribourg, Switzerland, where he spent a year studying philosophy and anthropology. He later studied letters and political science at the Institut Albert-le-Grand in Angers, receiving his bachelor's degree with honors in 2009. His degree was issued by Université d'Angers,

During the summer of 1997, Guillaume participated as a member of Luxembourg Scout Movement in a humanitarian camp in Nepal. He was involved in a reforestation project and other actions for the benefit of less fortunate communities. In 2017, he joined the board of directors of the World Scout Foundation to support the development of scouting around the world.

He previously served as the Lieutenant Representative (Regent) for his father, Grand Duke Henri, from 8 October 2024, until his accession to the throne.

Marriage and fatherhood

On interviews for his 30th birthday, he stated that he was in a relationship with a "dear miss" that had been going strong for more than a year but needed more time to evaluate their possible future. On 26 April 2012, the court announced the engagement of the Hereditary Grand Duke to the Belgian Countess Stéphanie de Lannoy. The civil wedding took place on 19 October 2012; the religious wedding took place on 20 October 2012, at the Notre-Dame Cathedral. In 2026, the wedding resurfaced in the controversy involving the relationship of Mette-Marit, Crown Princess of Norway, and Jeffrey Epstein, after media reports highlighted a remark in which Mette-Marit told Epstein that the wedding was boring her to death.

Guillaume and Stéphanie have two sons, who are first and second in the line of succession to the throne of Luxembourg:

  • Charles Jean Philippe Joseph Marie Guillaume (born 10 May 2020)
  • François Henri Louis Marie Guillaume (born 27 March 2023)

Reign

On 8 October 2024, as had been announced by Grand Duke Henri on his Official Birthday that year, Guillaume was appointed as lieutenant-representative (regent). Under this capacity, he assumed a number of his father's constitutional powers, such as the swearing in of ambassadors and the signing of Grand Ducal Decrees. This is traditionally the first step in the abdication process in Luxembourg, as both Jean (1961–1964) and Henri (1998–2000) have previously served in the position. On 24 December 2024, during his Christmas message, Henri announced that the abdication would take place on 3 October 2025.

Guillaume acceded to the throne on that date, becoming Grand Duke of Luxembourg. He chose to be known as Guillaume V, thus emphasising the previous four Luxembourgish Grand Dukes named Guillaume (or William in English): Guillaume I, Guillaume II, Guillaume III, and Guillaume IV.

On January 23, 2026, in an audience at the Vatican, he met with Pope Leo XIV, along with his wife, Grand Duchess Stéphanie. During the meeting, they emphasized the excellent relations between Luxembourg and the Holy See, accompanied by their sons, Princes Charles and François, marking the couple's first official visit since the succession to the Grand Duchy on October 3, 2025.

Titles and honours

Honours

National honours

  • 60px Co-Grand Master (since 3 October 2025) and Knight of the Order of the Gold Lion of the House of Nassau (7 October 2000)
  • 60px Grand Master (since 3 October 2025) and Grand Cross of the Order of Adolphe of Nassau (11 November 1981)