Guillaume, Hereditary Grand Duke of Luxembourg

At the occasion of his 30th birthday, he gave interviews during which stated that he was in a relationship with a "dear miss" that had been going strong for more than a year but insisted that they need some more time to evaluate their possible future.

Prince Guillaume, Hereditary Grand Duke of Luxembourg (Guillaume Jean Joseph Marie; born 11 November 1981), is the heir apparent to the crown of Luxembourg, holding the position since his father's accession in 2000.

Prince Guillaume was born on 11 November 1981 at the Grand Duchess Charlotte Maternity Hospital in Luxembourg City and is 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.

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 1999, he participated in a charitable mission in Aguascalientes to provide the educational and social assistance to young people in one of the most deprived areas in Mexico.

Guillaume has been heir apparent to the crown of Luxembourg since his father's accession in 2000.

If he succeeds to the grand ducal throne, he will reign as Guillaume V (English: William V).

After having chaired the Kräizbierg Foundation, which works for people with disabilities, for more than 10 years (2000–2011), the Hereditary Grand Duke accepted the title of honorary president in March 2011.

Guillaume's education includes Lycée Robert-Schumann in Luxembourg; 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.

He began his higher education studies in the United Kingdom where he studied at University College, Durham and Brunel University, both in England.

Guillaume became the honorary chairman of the Board of Economic Development of the Grand Duchy of Luxembourg, an agency for economic promotion and development, in March 2001.

Sworn in December 2002 as an officer in the Luxembourg Army, Prince Guillaume holds the rank of colonel.

The Hereditary Grand Duke completed internships at the Belgian Chemical Union in 2003, at the Deutsche Bank in London in 2004, and at the Spanish branch of ArcelorMittal in 2005.

He has also been a member of the Council of State since 24 June 2005.

He attended the Millennium Conference at the United Nations headquarters in New York City in 2005.

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, as a result of a partnership agreement between the two schools.

Prince Guillaume also worked at the European Commission and the Permanent Representation of Luxembourg to the European Union in Brussels in 2012.

The Hereditary Grand Duke is patron of the Luxembourg Cycling Sport Federation, Youth Hostels Central, National Association of Road Victims, Chamber Orchestra of Luxembourg, Youth Harmony Orchestra of the European Union, as well as to Young Entrepreneurs Luxembourg and Special Olympics Luxembourg Associations.

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 Friday, 19 October 2012; the religious wedding took place on Saturday, 20 October 2012, at the Notre-Dame Cathedral.

Since 18 January 2016, the Hereditary Grand Duke has been a member of the board of directors of Europäische Stiftung Kaiserdom zu Speyer Foundation.

He is also a member of the board of directors of the Fondation du Grand-Duc et de la Grande-Duchesse.

On 2 July 2021, Prince Guillaume, with his wife and son, inaugurated the Ettelbruck Agricultural Fair 2021.

On 12 July, he and his family visited Luxembourg nursing homes to meet elderly people and ensure their well-being during COVID-19 pandemic.

At each of their visits, the couple expressed their gratitude to the staff of the nursing homes for the efforts made in maintaining a warm environment around the residents, throughout the pandemic.

In 2017, the Hereditary Grand Duke joined the board of directors of the World Scout Foundation to support the development of scouting around the world.

From 2018 until 2019, Prince Guillaume attended a postgraduate training at the Royal College of Defence Studies (RCDS) in London.

Guillaume and Stéphanie have two sons, named Charles (born 10 May 2020) and François Henri Louis Marie Guillaume (born 27 March 2023), who are second and third in the line of succession to the throne of Luxembourg, respectively.

Guillaume is interested in music and sports; he plays the piano and enjoys football, swimming and volleyball.

He speaks Luxembourgish, French, German, Spanish and English.

He regularly represents his parents in many foreign activities.

His style and title in full is: His Royal Highness Prince Guillaume Jean Joseph Marie, Hereditary Grand Duke of Luxembourg, Hereditary Prince of Nassau, Prince of Bourbon-Parma.