You have heard of “Indira is India”. In the same way “Mugabe was Zimbabwe”.
He was effectively the only leader of independent Zimbabwe and did improve the conditions of the common people in the early years of his rule. Later things did not go well and he faced widespread opposition before the armed forces deposed him in 2017, after 37 years in power.
You can read an overview of his life here:
And he features in many lists of durable leaders:
He is only 98th on this list, as he lived to be 95 years and 195 days.
Many of those higher in this list are little-known or from little-named countries.
The longest-living well known persons here would be
Y Nakasone, PM of Japan in the 1980s, still living at 101+
Perez de Cuellar, PM of Peru and UN Secretary-General, still living at 99+
Prem Tinsulananda, PM of Thailand, lived to be 98+
The Indian duo of Gulzarilal Nanda and Morarji Desai both crossed 99.
Also see this:
Note Mahathir Mohammad, serving as PM of Malaysia at 94+
followed by Queen Elizabeth 2 at 93+
Robert Mugabe was President until he was deposed at 93+
However, Malawi’s Hastings Banda was President for Life until 1994 when he was deposed at 96+
In contrast, the oldest US President was Ronald Reagan who was 77+ at the end of his second term. The longest lived US President is Jimmy Carter (born Oct 1, 1924 and presently 94+. Earlier this year he overtook George Bush (senior) who lived to be 93+