Finland's Sanna Marin, world's youngest PM

Marin will become the youngest-serving leader of a government in the world, beating out Ukraine's 35-year-old prime minister, Oleksiy Honcharuk. She might not hold that title for long, however. Like New Zealand Prime Minister Jacinda Ardern _ who is 39 _ Marin is a new mother, having given birth to a daughter last year.