It is not unusual to find top executives who enjoy reading biographies of extraordinary people. Much can be gleaned from them if the author isn't a sycophant. Decent autobiographies are equally helpful.
Some (auto)biographies that I believe have hidden gems for execs are:
The LBJ biographies by Robert Caro. I'm partial to the first volume. An extraordinary story of a young man on the make who became a professional "son" in order to advance. LBJ was at once repugnant and compelling.
Chronicles of Wasted Time by Malcolm Muggeridge. Muggeridge's career as a journalist in the thirties and forties brought him into contact with some of the ugliest regimes and most fascinating people on earth. Very witty stuff.
Churchill by Piers Brendon. This can be hard to find. A quick and insightful look at the greatest leader of the 20th century.
Six Crises by Richard Nixon. Nixon wrote beautifully and never better than in this review of his experiences in the years before he became president.
The Kennedy Promise by Henry Fairlie. A British journalist looks at the magic - and limitations - of JFK's charisma.
These are just a few and I'm sure that major ones are missing. Submit others and I'll post a master list.