Donald Rumsfeld, who was the US Secretary of Defense in the presidencies of Ford and Bush (jr) has died at the age of 88.
Trivia notes: he is the only person to have been the Defense Secretary twice. The first time (1975-77) he was the youngest to hold the post. The second time (2001-06) he was the oldest.
He is remembered for his quotations, notably the one about known knowns and unknown unknowns. The more famous ones can be seen here: