A twentieth-century American novelist, he is best known for Auntie Mame: An Irreverent Escapade. He published a sequel, Around the World with Auntie Mame, in 1958.
He joined the American Field Service during World War II and worked in North Africa and the Middle East as an ambulance driver.
The first edition of Auntie Mame spent 112 weeks on American bestseller lists and sold over 2,000,000 copies in five different languages.
He grew up in Illinois. With his wife, Louise Stickney, he had two children.
After retiring from writing, Dennis worked as a butler for McDonald's restaurant founder Ray Kroc.