King Juan Carlos of Spain, who after 39 years as head of state abdicated the throne in favor of his son and the current monarch, Felipe VI, celebrated his 80th birthday on Friday.
Between 1975 and 2014, Juan Carlos oversaw Spain's sometimes fragile but relatively peaceful political transfer of power from an authoritarian military dictatorship to a fully-fledged European parliamentary democracy, an era described as "the Transition."
Juan Carlos de Borbon was born on Jan. 5, 1938 in Rome, Italy, where his family lived in exile.
His abdication in June 2014 was to some extent prompted by a series of scandals that marred the last years of his reign.
Juan Carlos had been proclaimed king by dictator Gen. Francisco Franco's moribund Parliament, and in his acceptance speech he addressed his fellow citizens asking them for generosity, a sense of vision and national unity to open together "a new era in the history of Spain."
In Aug. 1948, his father, Juan de Borbón, and Franco agreed the young prince would be educated in Spain and groomed to become its future king.
Spain's royal family had lived in exile since the 1931 proclamation of Spain's second republic.
In 1969, Franco backed and appointed Prince Juan Carlos as his successor, something that happened after the hard-line dictator's death in Nov. 1975.
Despite resistance by the Franco regime's hangers-on, Juan Carlos persevered in his vision of becoming "King of all Spaniards," albeit aware he was being closely watched by the former government's military chiefs as well as by a then still-clandestine political opposition.
On Dec. 6, 1978, Spain voted in the current Spanish Constitution, drafted the previous year by a democratically elected parliament, establishing Spain as a parliamentary monarchy.
A key move was Juan Carlos' appointment of Adolfo Suarez as Spain's first post-dictatorship prime minister.
Also outstanding was his personal role during an attempted military coup on Feb. 23, 1981.
In his televised address to the nation, Juan Carlos distanced himself from the coup plotters, a move that earned him widespread prestige at home and abroad.
The king also often acted as Spain's top diplomat, in particular, during Spain-sponsored Iberoamerican summits.
However, his public image began deteriorating in Spain after the judicial scandal that landed his son-in-law Iñaki Urdangarin in the dock on corruption and fraud charges alongside his own daughter, Infanta Cristina.
While Urdangarin was convicted of embezzling about 6 million euros ($7.2 million) of public funds through a company he had set up as a nonprofit foundation, Cristina was absolved of tax fraud charges.
This was followed by a series of surgical operations due to the king's failing health.
Another scandal to engulf Juan Carlos in April 2012 was a private trip to Botswana to hunt elephants while acting as president of Spain's branch of the World Wildlife Fund.
During that trip, which had taken place without the government's knowledge, he fractured a hip and had to be flown back to Spain at public expense for emergency surgery.
The scandal was such he was forced to apologize in public.
Since he abdicated, Juan Carlos has maintained a discreet background role although he keeps an institutional agenda and has represented Spain abroad on 19 occasions, half of them in Iberoamerica.