The Norwegian Royal Family is the reigning royal house of Norway, known as the House of Glücksburg. The family is headed by King Harald V, who ascended the throne in 1991. His wife, Queen Sonja, is the first commoner to marry into the Norwegian royal family. They have two children, Crown Prince Haakon and Princess Märtha Louise. Crown Prince Haakon is the heir apparent and is married to Crown Princess Mette-Marit. The royal family plays a ceremonial role in Norway, representing the country at official events and promoting various charitable causes. They are also involved in cultural and social issues within the nation.