Who is the Monarch of Luxembourg?

Guillaume V, Grand Duke of Luxembourg has been Monarch of Luxembourg since Oct 3, 2025.

Who is the longest-serving Monarch of Luxembourg?

William III of the Netherlands, with 15,226 days in office.

Constitutional monarchyLiberal democracy

Guillaume V, Grand Duke of Luxembourg

Monarch · 332 days in office

Longest-serving

William III of the Netherlands

15,226 days

Shortest-serving

William I of the Netherlands

9,337 days

Average tenure

12,282 days

Guillaume V, Grand Duke of Luxembourg: 97% below average

#	Name	Took office	Left office	Days
2	William III of the Netherlands	Mar 17, 1849	Nov 23, 1890	15,226
1	William I of the Netherlands	Mar 16, 1815	Oct 7, 1840	9,337

Officeholder history via Wikidata. Multiple rows for one person indicate separate terms.

Who is the Monarch of Luxembourg?: Guillaume V, Grand Duke of Luxembourg has been Monarch of Luxembourg since Oct 3, 2025.
Who is the longest-serving Monarch of Luxembourg?: William III of the Netherlands, with 15,226 days in office.