Emmanuel Macron, who is 39 years old, will join the ranks of the world's youngest leaders when he is inaugurated as president of France on Sunday. Other leaders past and present, elected and otherwise, were even younger when they came to power. Among the leaders who were under 45 when they took office are:
Moammar Gadhafi, Libya
The late Libyan leader was 27 when he seized power in 1969. The dictator held on to power until he was ousted in 2011. He was captured and killed a few months later.
Fidel Castro, Cuba
The Cuban revolutionary leader, who died last year, was 32 when his rebel forces took control of Cuba. He ruled for nearly five decades as one of the world's last communist leaders.
Kim Jong Un, North Korea
The North Korean leader is quite possibly the world's youngest ruler. But, like so much about his country, his exact age remains something of a mystery. He is thought to be 32 or 33. Mr. Kim, the third generation in North Korea's ruling dynasty, assumed power in December 2011 upon the death of his father, Kim Jong Il.
Daniel Ortega, Nicaragua
Mr. Ortega was 33 when he became a leader of the junta that ran Nicaragua after the Sandinista revolution ousted dictator Anastasio Somoza in July 1979. In November 1984, just before his 39th birthday, Ortega was elected president. He was voted out in 1990 and then won re-election in 2006, 2011 and 2016.
Gamal Abdel Nasser, Egypt
Mr. Nasser was 38 when he became president of Egypt in 1956. He nationalized the Suez Canal and championed the pan-Arab cause, becoming one of the world's most prominent anti-imperialist figures by the time of his death in 1970.
Sigmundur David Gunnlaugsson, Iceland
In Iceland, Mr. Gunnlaugsson became prime minister at 38 in 2013. He resigned in 2016 after details of his offshore financial holdings were revealed in the Panama Papers leak.
Rajiv Gandhi, India
Mr. Gandhi was catapulted to India's highest office at age 40 when his mother, Prime Minister Indira Gandhi, was assassinated in 1984. He began his premiership with promises of modernizing India's creaking government. Within a few years, he was forced to resign amid allegations of taking bribes in an arms deal. He was assassinated in 1991 while campaigning to return to office.
Mustafa Kemal Ataturk, Turkey
Mr. Ataturk, the revered founder of the Republic of Turkey, was 42 when he became the country's first president in 1923. The revolutionary leader's last name means "Father of the Turks."
John F. Kennedy, United States
Mr. Kennedy was the youngest person ever elected to the presidency of the United States. The wealthy senator and war hero was 43 when he took the oath of office in 1961. But he was not the youngest US president ever – that was Theodore Roosevelt, who was 42 when he took over after the assassination of President William McKinley.
Justin Trudeau, Canada
Mr. Trudeau was elected as Canada's prime minister in 2015, when he was 43. Like Rajiv Gandhi, he had a strong family connection to the office. His father, Pierre Trudeau, also served as prime minister.
Tony Blair and David Cameron, Britain
Mr. Blair was 43 when he was elected Britain's prime minister in 1997 – the country's youngest leader since 42-year-old Lord Liverpool in 1812. Mr. Cameron was also 43, but a few months younger than Blair, when he became Britain's leader in 2010. Things did not end well for either: Blair led the Labour Party to three straight victories, but was discredited for joining the US-led invasion of Iraq. Cameron resigned last year after failing to convince Britons to remain in the European Union.