Finland's Sanna Marin, 34, will be the world's youngest prime minister in office when she is sworn in tomorrow. 

Here are the nine youngest leaders serving in the world today:

1. Ukraine: Lawyer Oleksiy Goncharuk was named prime minister in August 2019, aged 35, by President Volodymyr Zelensky, himself only 41.

Oleksiy Goncharuk was named Ukraine prime minister earlier this year

2. Salvador: Conservative businessman Nayib Bukele was sworn in as president in June 2019 aged 37.

Nayib Bukele is the 46th president of Salvador

3. Andorra: Former justice minister Xavier Espot Zamora became the head of government of the small territory between France and Spain in May 2019 aged 39.

 French President Emmanuel Macron (L) and Andorra's Prime Minister Xavier Espot Zamora (R) both became leaders aged 39

4. Costa Rica: Carlos Alvarado, a journalist and former labour minister, won elections to become president in May 2018 aged 38.

Carlos Alvarado was first elected as a Chilean MP in 2014

5. New Zealand: Jacinda Ardern was 37 years old when she was sworn in as prime minister in October 2017.

Jacinda Ardern is the 40th Prime Minister of New Zealand

6. Ireland: Leo Varadkar became Ireland's youngest Taoiseach in June 2017 when he was aged 38.

Leo Varadkar was first elected to Dáil Éireann in 2007

7. France: At the age of 39, one-time investment banker Emmanuel Macron became France's youngest president in May 2017.

8. Estonia: Centrist Juri Ratas was named prime minister in November 2016 aged 38. He took over from Taavi Roivas, who was 34 when he took office in 2014.

Juri Ratas also served as mayor of Estonia's capital, Tallinn, from 2005 to 2007

9. Malta: Prime Minister Joseph Muscat took power in March 2013 at 39 years old.

Joseph Muscat was previously a member of the European parliament from 2004-2008

Excluding democratic governments, other notable young leaders include North Korea's Kim Jong-un, 35, and the emir of Qatar, Sheikh Tamim bin Hamad Al-Thani, 39.

Bhutan's King Jigme Khesar Namgyel Wangchuck, today aged 39, took power in 2006 when he was just 26.