King Juan Carlos of Spain, the man credited with steering his country towards democracy after the death of the dictator Francisco Franco in 1975, is to abdicate.
The announcement was made by Spain's prime minister Mariano Rajoy.
The Week
Escape your echo chamber. Get the facts behind the news, plus analysis from multiple perspectives.
Sign up for The Week's Free Newsletters
From our morning news briefing to a weekly Good News Newsletter, get the best of The Week delivered directly to your inbox.
From our morning news briefing to a weekly Good News Newsletter, get the best of The Week delivered directly to your inbox.
The 76-year-old king will be replaced by his son, Felipe.
According to the BBC, Juan Carlos was long seen as "one of the world's most popular monarchs".
Juan Carlos became king on November 22, 1975, two days after the death of Franco, who had named him as his successor.
Over the subsequent months, the king quickly dismantled the institutions of Francoism – a move which made him a constitutional monarch under a newly democratic system. In 1981, Juan Carlos stood firm against a military coup, which, according to The Times, "won him international respect – and the adoration of his people".
Rajoy said that Juan Carlos had been a "tireless defender of our interests".
The king's popularity "dipped" in recent years, The Guardian says, after his reputation was diminished by a spate of scandals. In 2012, during the height of the financial crisis, Juan Carlos took a lavish elephant-hunting trip to Botswana. And in February this year his youngest daughter, Princess Cristina, became the first member of the royal family to appear in court as a suspect in a criminal case. Her husband is currently under investigation for embezzlement.
A poll in January found that two thirds of Spanish people believed that abdication was the best option for the king. It also found that the same percentage had a "good" opinion of Prince Felipe.