The youngest leader was, appropriately enough, the UK Prime Minister William Pitt the Younger who was 24 when elected.
The youngest leader currently is Kim Jong-un who is 33 years old.
The oldest leader is Robert Mugabe, who will soon be 92.
The longest lived documented leader since 1800 was Chau Sen Cocsal Chhum, prime minister of Cambodia in 1962, who was 103 years, 135 days when he died in 2009.
There have been fourteen state leaders who reached 100. The oldest still living is Piet de Jong, prime minister of the Netherlands 1967 to 1971. He is 100 years, 317 days old.